TouchMyApps » ALO All Things iPhone and iPad for those who like to Touch. iOS App reviews, News, New Apps, Price Drops and App Gone Free Tue, 21 Jul 2015 20:40:30 +0000 en-US hourly 1 ALO Audio’s The International headphone amp/USB DAC in review Mon, 25 Feb 2013 07:28:46 +0000 It’s off to the races again. This time, ALO have suited up their youngest and most exciting audiophile offspring, The International. This amp features at 24/96kHz USB DAC, discrete analogue/digital sections, a powerful battery, extremely low noise floor, and the must-have feature of the decade: balanced input and output. With all that under the bonnet, … Read more]]>

ALO The International BW

It’s off to the races again. This time, ALO have suited up their youngest and most exciting audiophile offspring, The International. This amp features at 24/96kHz USB DAC, discrete analogue/digital sections, a powerful battery, extremely low noise floor, and the must-have feature of the decade: balanced input and output. With all that under the bonnet, you can be sure this youngster will turn heads as it swishes by.


Battery: 1600 mAh Lithium-Polymer
Dimensions: 71.5 mm x 85 mm x 25.5 mm
Battery Play Time: 14-16 hours (Amplifier) 8-10 Hours (Amplifier + DAC)
Battery Recharge Time: 3 hours
Frequency Response : +/- 1 dB:10-25,000 Hz
Colour: black or silver

Output Power – Balanced:
130 mW into 32 Ohms
200 mW into 50 Ohms
330 mW int 600 Ohms
660 mW into 300 Ohms
Input Impedance:

Output Power – Unbalanced:
130 mW into 32 Ohms
160 mW into 300 Ohms
200 mW into 50 Ohms
83 mW into 600 Ohms

Manufacturer: ALO Audio
Product: The International
Price: 599$

ALO The International accessories ALO The International box ALO The International BW-2 ALO The International BW ALO The International iphone ALO The International National

Build Quality
Every current-generation ALO portable amp is built like a tank. The International is no exception to that rule. It retains the essentials of The National: 2mm hex screws, a thick mounting chassis, and solid main board. Of course, The International also touts a fine 24/96kHz USB DAC, which is located on a 2nd main board( separate from the analogue section), as well as balanced input/output circuitry.

Chassis size has shrunk, but build quality has stayed the same. Inside, solder joints are robotically precise and the boards snap cleanly into their 9-pinned joint section. The battery clips into the main board. Presumably, it could be replaced by a dextrous user, however, it’s bum is glued to the bottom of the chassis, so it requires experience with a mechanic’s spatula and glue solvent. The volume pot follows the RX, incorporating tracking and power on/off functions into a single part.

Ergonomics and Polish
Every iterative ALO amp is better than its predecessor. The International bested the old RX with a hard-to-scratch matte chassis and perfectly spaced in/out panel. Later RX amps bested their predecessors with more secure connections and switches. The International finishes the tradition with a fiercely compact design that is packed with features while remaining simple to use.

The on/off lamp still shines demurely, equally ready for a bedside rig or a night out. Single-ended ins and outs are spaced far apart and are sunk modestly into the faceplate. Even ALO’s fattest pipe cables will work. Balanced ins and outs are split front to back. The volume pot is precisely aligned. The ALO logo reads horizontally when the amp is off; the arrow graphic between ‘ALO’ and ‘audio’ indicates where on the volume scale the amp is set. The International does all this without a blinding array of letters.

Understated and rational layouts are chief in ALO’s designs. What can’t be stated enough is how much smaller The International is than The National, and of course, The Continental. Normal-sized hands can completely cup ALO’s latest, while they would do no better than palming The National.

Inside, the main board is laid out in logical, clean lines. All parts are easy to read, and with the snap-in design of the analogue/digital boards, taking a greasy look at at any part is simple. As mentioned above, to remove the battery, you will need to use a solvent and a workman’s spatula on the chassis-side. Otherwise, no specialised tools are needed to access any part.

Passing over any part in the audio chain would be ingenuous. Chiefly, The International is ALO’s first portable DAC. (Of course, The amazing Pan Am sports a USB DAC as well, but primarily, it is a desktop amplifier.) Plug its USB port into a Mac or PC and your computer preferences will display “ALO(HD)Audio” rather than a generic label. No drivers are necessary.

Better yet, the DAC chip receives its power from the internal battery, not from a computer’s bus system. That means that it works directly on an iPad via the Camera Connection Kit, or on a jailbreaked iPhone or iPod touch without necessitating an external USB hub. To get iPhone and iPod touch devices working, you will need the 30-pin Camera Connection Kit, BigBoss Camera Connector app (99 cents), and iOS 5. I’ve not been able to get iOS 6 to work with BigBoss’s Camera Connector app and either version of Apple’s Camera Connection Kit with the iPhone or iPod touch. When/if support for the new devices are made available in BigBoss, I’ll update this section.

Currently, there are few DACs that work directly with iOS devices, mainly because they need more voltage than the iPad can supply. The International doesn’t stand alone, but it stands with the most poise among a rather small number of truly portable-friendly amp/DACs.

As you will notice, the International also sports balanced input and output. To enable balanced input, flip the switch the switch at the back from USB to the up arrow. No matter the input, either single ended or balanced can be used from the front panel. It’s automatic (cue Utada Hikaru’s early 2000 mega hit), and easy as pie. Single ended input takes precedence over balanced or USB. If you with to use either, unplug the singled ended bits.

Suffice it to say that I didn’t expect the diminutive The International to spit with such depth and power. It puts roughly the same amount of slam into high Ω headphones such as the DT800 600Ω as The National. Thus, it is perfectly home plugged into a HiFi.

Through the years, ALO have delivered amps with respectable to excellent headphone out performance. The Rx, for instance, remains a benchmark at TMA and other enthusiast publications. However, it tends to output more background noise than is comfortable for IEM use. Even The National outputs a slight bit more noise than many rivals. Still, both of those amps perform very well for an unbelievably wide range of headphones.

The International puts an end to the days of background noise. In fact, on low gain, background noise is lower than the IEM-specific hippo cricri and cricri+. Noise levels are similar to the iBasso T3D, an amp that I praise endlessly for IEM usage.

‘Zero’ volume corresponds to about 10 o’clock on the volume pot. There are about 45 minutes of play on the pot before sound comes in at 10:45. With ultra-sensitive earphones such as the Sleek Audio CT7, I feel comfortable listening to volume levels of up to 12 o’clock with older recordings, and 11:45 with newer recordings. In addition, there is no volume pot scratching and when turned on/off, the amp doesn’t thump loudly. Instead, there is a tiny audible blip, but nothing that hurts the ears, phones, or amp.

Essentially, users of sensitive IEMs will have roughly one to one and a quarter hour turns to enjoy their music, possibly more. (Remember, I listen to low volume levels.) That one and a quarter turn is also a reassuring ordeal. The volume pot doesn’t turn at the slightest nudge. It stays in position unless deliberately adjusted and therefore, is safe for blind pocket use.

The only amp in recent memory that gives that much control to sensitive earphones is the IEM-specific Headamp Pico Slim. The Pico Slim, however, has very little reserve when used with full-size headphones, and, it suffers to listener to quite an on/off power thump.

The International has no such constraints on its output. Where its low gain is a virtual playground for sensitive IEMs, its medium and high gain settings are all business. For most headphones, high gain is a mere academic setting. Even the DT880 600Ω gets plenty of volume on low gain, and on medium, a little more headroom. On high gain, only at a setting of 95% on the volume pot does The International show signs of fatigue. 90% will render strong dynamics and no hint of IMD.

Similarly, the medium-low Ω ES7 turns into a desktop speaker when plugged into The International. The amp’s circuitry begins to be troubled by compressed dynamics on high gain and set at 70%. After 75%, IMD makes it impossible to listen to. Of course, at such volume settings, the amp is simply too loud for any ear. Power doesn’t quite reach Pan Am levels, but it gets as close as a battery powered portable amp will.

In terms of actual resolution, for the most part The International plays hardball. It is most comfortable with headphones above 40Ω, and demonstrates absolutely no load at around 60Ω, but with low Ω earphones, as well, it shows strongly, delivering generally high levels of resolution. Multiple armature earphones MAY trip up The International on certain, bass-heavy tracks, but not enough to remove my recommendation for earphone use.

The International’s clear background renders strong dynamic punch and contrast between frequency bands. Here, again, it reminds me of The National – a National with less distortion and slightly clearer dynamics.  Both amps tend to drop stereo separation when confronted with hard-to-drive low Ω earphones like the Earsonics SM2, but maintain good dynamic control. Harmonic distortion takes a 1000% uptick when the SM2 is plugged in, but never flares into veiling audibility. Very few amps deliver distortion values of less than 3% when coupled with the SM2.

In fact, other than delivered resolution to the lowest Ω earphone, The International handily steps up to the Rx. Users of low Ω IEMs may notice some low frequency loss in some music, and maybe a slight heat to the upper midrange, but it’s nothing big. Overall, ALO nailed with the International.

On USB input
As with nearly all portable USB DACs I’ve come across, optimal performance is achieved via analogue input. It’s not necessarily that there is more noise in the USB signal, it’s that actual signal quality is poorer. It’s not an ALO thing – it’s generally a non-CENtrance thing. In the case of The International, USB input curtails dynamic range and stereo image the most. Background noise is still kept low, and is certainly lower than the output of most if not all computers, but it isn’t as silent or high quality as either of the analogue inputs.

On Balanced VS Unbalanced
Balanced allows more current to hit a set of transducers than an unbalanced signal. Even in 2013, there are only a few balanced portable sources out there. On the iDevice front, Cypher Labs’ CLAS DB works its magic, while on the desktop front, there are many options to choose from.

The International will take a single ended analogue signal and split it into correct phases for balanced output. It will also do the same thing to a USB input signal. Balanced signals run in and out similarly. Every signal will pass the same Burrbrown DRV134ua output amplifiers that convert single ended signals to balanced signals. From a performance perspective, the balanced signal splits phases wonderfully even if the original signal is single ended. The International does a phenomenal job.

Its balanced signal gains several decibels of dynamic range and, a lower noise floor, and more power to high Ω headphones.

NOTE: for balanced armature earphones, a balanced signal may sound like a great idea, but it is only really good if the earphone transducers are made specifically to accept balanced signals. If not, the earphone’s sound will alternate greatly from the manufacturer’s ideals. It’s not as simple as slapping on a balanced cable. Whether you like that sound or not isn’t up for question; what is is if you can live with its effects. With the exception of ALO’s FitEar 334 there are very few balanced armature IEMs that are designed for balanced signals. Dynamic driver earphones and headphones, however, are another story. Both are run splendidly via The International.

Sound in a Nutshell
The International boasts low distortion, high resolution, a very low noise floor and decent to good stereo separation. There is enough power in it to blow headphones and eardrums to oblivion and still retain a high quality signal. It’s like a better The National with the added plusses of a balanced audio circuit and USB DAC. In ALO’s line, it is the amp with the lowest background noise floor, and therefore, a killer accessory for IEM users. The fact that it packs a wallop of a punch with voltage and current hungry headphones, too, is a wonderful surprise. Way to go ALO.

RMAA and Square Wave Test Disclaimer
Tests performed in this section reflect The International’s performance when connected to a specific set of output/input devices. They should not directly be compared to any other result. The input device is an Edirol FA-66. The output devices are: Earsonics SM2, Beyerdynamic DT880 600Ω, and Audio Technica ES7, which are connected in parallel to the output signal. All Tralucent T1 hardware tests will be posted in TMA’s forums. Source components are: Cypher Labs CLAS, an iPod nano 6G, and where noted, an iBasso DX100. Tests will appear in TMA’s forums.

Out and About
For its uses, The International is a small amp. It pockets friendlier than any ALO amp to date, employs a sturdy volume pot, and boasts excellent gain settings. It is fully recommended for all earphones/headphones you can throw at it whilst you sit on the train, bus, or walk about town. Thankfully, its matte casing isn’t easily scratched; simply wrapping it and your source with the included elastic bands is enough to safely keep things going all day. RF interference ins’t a big problem, either.

There’s no skimp in The International’s engineering regimen. This amp runs with the big boys while keeping up with IEM-specific midgets. Noise is stuffed way down and tracking errors are minimal. The plug-and-play simplicity of its fully battery-powered USB DAC means that it runs from pretty much any source, including iOS devices. If you’ve got 599$ waiting for the right piece of audio equipment, you likely won’t find a more comprehensive all-in-one deal than The International. There’s simply nothing The International can’t do – a fact that even ALO’s older siblings would be wise to note. Because what you are looking at is the amp, that, in capability-for-dollar values, simply runs circles around whatever’s out there.


- Excellent construction
- Extremely low noise floor
- Great resolution and power into high Ω headphones
- Good resolution for low Ω earphones
- Internal DAC’s power supplied by internal battery, NOT computer bus
- Excellent left/right tracking for all headphones
- Fully balanced in/out circuitry with measurably better performance

- Output resolution with low Ω earphones limited because of semi-high output Ω
- USB performance isn’t as good as line performance

Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

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ALO the Pan Am Headphone amplifier/DAC in Review Thu, 04 Oct 2012 16:46:11 +0000 After an evening of Ghostbusters, it’s hard to want anything more than a date with the Sigourney Weaver of 1991. Keymaster? That’s me. Hell yeah! But, returning to my desk, I am met by another comedy great – or the likeness of one. Indeed, Bender lives on in ALO’s Pan Am, a wonderfully competent full-size … Read more]]>

After an evening of Ghostbusters, it’s hard to want anything more than a date with the Sigourney Weaver of 1991. Keymaster? That’s me. Hell yeah! But, returning to my desk, I am met by another comedy great – or the likeness of one. Indeed, Bender lives on in ALO’s Pan Am, a wonderfully competent full-size headphone amplifier/USB DAC that just happens to, like Bender, enjoy galavanting around different spaces.

Expansive Sound Stage
Great Bass Response and Extended Highs.
Frequency Response 40Hz-30KHz +/- 1dB

16/24 bit Resolutions supported
8/16/32/44.1/48/96 KHz sampling rates supported
Wolfson Digital to Analog Converter Chip

ALO don’t supply a bevy of spec, but in reality, they don’t need to. If their amp works, it works. And, it like crossing dematerialiser beams, the Pan Am ‘cleans up’ exactly where it needs to. In fact, it is one of the most powerful desktop amps in its size category.

Contact ALO
If you’re pining for the Pan Am, hit up ALO Audio. They’re out on the west side of the USA in beautiful Oregon. Here are their contact details:

1810 SE 10th Ave. Unit B
Portland, OR 97214
Phone: (971) 279-4357

You can also check out their new blog, which is a great mix of audiophile and music foolery. And is very fun to read. In fact, every aspect of their current website is ordered quite precisely: reviews are prominent, new products are well shot and come up quickly. Ordering and interacting with their website is a delight – an experience not unlike Apple’s homepage.

But let’s get onto the review.

ALO-Audio-Pan-Am-Bender-face ALO-Pan-AM-back ALO-Pan-AM-ballasts ALO-Pan-AM-box-set ALO-Pan-AM-covers ALO-Pan-AM-ES10 ALO-Pan-AM-forza-alo ALO-Pan-AM-front-ports ALO-Pan-AM-rear-ports ALO-Pan-AM-Valves-top ALO-Pan-AM-valves

Build Quality
If you’ve been following TouchMyApps headphone reviews, you know that ALO have featured prominently in 2012. ALO are simply on a winning streak: they make quality products that by and large, have no competition. It would be a shame to leave any potential ALO podium empty.

Enter the Pan Am. This amp handles, looks, and feels very much like either The National or The Continental. It shares the same volume pot, gain and power switches, very similar face plates and input/output ports (though this time, the a 6,3mm jack made the cut). And, in terms of footprint, the Pan Am is just three millimetres longer than The National and about twice the volume.

Its aluminium case is the same sturdy chunk. If you’re out and about with the Pan Am and things get ugly down at the bank, you could crack some would-be robber’s skull with it. Good riddance.

It stacks perfectly with its accessories: Gateway and Passport, each of which come with their own power connectors that mate to the Pan Am in with almost uncanny precision. Horizontal channels are dug into the top of each unit; their inverses run along the bottom. They fit together like a set of well-loved Legos.

The front and back plates of the Gateway and Passport rise flush with the extruded aluminium chassis so that when mounted, the Pan Am (or other accessory) doesn’t slip. Genius.

‘Round the back, ALO have fitted RCA, 3,5 stereo mini, and USB inputs. The input selector looks exactly like the volume pot; the familiar 12V input sinks into the other side. You have seen this before.

The 61J valves sit firmly in shallow-seated. They are easily rolled (trust me, you will have fun with this). And, in the case of radio or other interference, you can cap the valves with the included aluminium gowns.

Overall, this design is very well thought-out. That said, handle the RCA jacks with care. They aren’t bolted onto the case; constant pushing and pulling could damage their contacts. The only other nit to pick is the 12V mains and battery leads, which bumble around a little in their ports. Again, just play nice and you will have no problems.

Ergonomics and Polish
Forget Industrial. The Pan Am pushes the cute angle. It’s an amp for today’s up-and-coming audiophile (and fans of yesterday’s scifi cartoons). It looks great on a desk or near the TV, and with its tote bag, on your hip. I can picture a young music-loving chap at Starbucks or Juleno, balancing a pair of Grados on his head, the Pan Am feeding his ears. I could imagine his love interest next to him with a pair of Grados on his/her head, sharing the 2nd output – I could except that only one output works at a time. Bugger, love bugs.

Dates and, okay, RCAs aside, the Pan Am is a rocking unit. The ins, the outs, the volume, the gain, and the input switch are all intelligently designed. Even getting into and out of the amp (if you like to dismantle your stuff) is easy. Ditto Gateway. Ditto Passport.

Maybe more than foolproof, the Pan Am is all-inclusive. You can even buy quality ALO cables for it, rig it all up, and merely attach headphones. (By the way, you can also buy Audeze LCD-2 from ALO…)

From desktop to floor to train to bag to deck to tent to tray to the pit of hell, this amp will go with you.

Forza Audioworks RCA cables and ALO 3,5mm and USB

You already know this thing works as a DAC and an amp. You also know that you can get the upgraded power supply (Gateway) and the battery (Passport) for the it. The Passport will give you a good 8-10 hours of battery life, so your work day, or your play day are pretty much covered.

It is also my number 1 recommended accessory. It completes its main product like no other accessory can. That is, from ALO and from the competition. It’s simple: the Pan Am and the Passport were made for each other.It turns your desktop amp into a walkabout amp. Amazing.

The included DAC works in both 16 and 24 bit word length and supports up to 96 KHz resolution audio when fed by USB. Unfortunately, the Pan Am’s DAC draws its power from USB and uses too much power for iDevices to run it. No BigBoss CameraConnector trickery will get your iDevice to play nice with any but the analogue inputs of the Pan Am. Of course, if you plug the DAC into a powered USB bridge, then you can use its DAC with your favourite device.

Sound impressions
For this portion of the review, my impressions will, in the main, be based on listening impressions taken with the Beyerdynamic DT880, and here and there, with the LCD-2 and HD600. Here goes…

Space (or is it bass?) is the first thing that gets me – it got Bender, too, many times, but that’s another story. The Pan Am’s linear stereo image carves my favourite recordings into deliberate chords and lines. Via rather spacious-sounding headphones such as the DT880, powerful and detailed bass drives music. It corrals mids and highs between its pillars while never stepping on its own – rather heavy – feet. Interestingly, songs like Paul Oakenfold/Ice Cube’s ‘Get Em Up’ weather the Oregonian sound rather well.

Hip hop fusion is one thing. Smoother genres are even more interesting. The Pan Am’s bass comes across dryer than bass in the Porta Tube+, but is ever so much more PRAT-full. It yawns over Boards of Canada’s methodic chasms while preserving detail and space. Paucity afflicts no frequency.

Bass drives, mids steer, and highs check the road for bends and roadkill. The delicacy with which each presents itself in creating a lucid whole is perfect (as in complete). And yet, behind – or perhaps I should say over – everything is a light layer of fuzz. It’s not pulled tight into smothering corners or stuffy. It’s just comfy. Still, while I consider this fuzz to be characteristic of valve amps, there are do’s and don’ts to fuzz. If that fuzz bunks up the midrange, something is off. If it fuzes bass or treble, something is off. Typically, my sources are flat, and since I am rather more of a solid state fan than I am a valve fan, I forget the pleasures that a little fuzz can bring. Fuzz a la the Pan Am is like Japanese sansho pepper: citrusy, spicy, but light, and good in everything but pudding. It won’t make you cough, or stop up your favourite music, not matter the speed.

That said, There are a few genres that may may prefer a different flavour. One is speed metal. The other is speed trance. Simply put, these two genres prefer solid state and impeccable performance to atmosphere and spice. Only solid state can deliver that.

Genres that have grown on me (and flown through the Pan Am) are Intelligent Dance Music (IDM), vocal and instrumental jazz, and hip hop. Overly technical genres such as trance and symphonic music do sound wonderful paired with the Pan Am, but then, I feel that listening styles change, too. One doesn’t relax the same way to classical as one does to Faithless or MC Solaar or even Classified, where slumped as you are in your sofa, your foot is pumping away on your carpet.

Mids and highs present themselves in much the same way: melodic, realistically detailed, and up front. Musical stage focus narrows mostly between the ears and projects forward as if what you were hearing came from a stage about a half a metre in front of your eyes. That is cozy. It’s not cozy in quite the same way the Continental is, but in comparison to the expansive musical stage of the ALO Rx, for example, it is intimate. A lesser amp would be drowned by the intimacy. The Pan Am’s linear separation of channels along the frequency plane strengthens the dynamics.

As does the lack of ringing. As long as you have the right headphones fastened to your ears, resolution isn’t impeded by internal stop. Typical to all valve-based amps of any price, overall resolution falls well below the bounds of 16-bit audio. But, then again valves aren’t primarily about resolution. They are about power. This amp supplies current and voltage by the bushel as long as the output headphones are high Ω.

In which case, you get that lovely, smooth, but heavy-footed low bass.

And that, friends, is the grease that lubes this robot. Bass, like or hate the word, as gentle as it is pronounced, is the Pan Am’s drivetrain. And I love it.

Sound performance
The Pan Am is duly impressive. Noise levels are low enough to use with sensitive earphones, and left/right balance is a cinch for all but the most sensitive earphones on the market. Take for instance the Heir Audio 3 & 4.Ai models, which can show up noise in an iPhone 4. When paired with the Passport, there is little to no noise through their sensitive transducers. Ditto FitEar ToGo! 334. And the Grado GR8. Quite an amazing feat.

The included wall wort, on the other hand, exhibits some noise, but, generally, it isn’t bothersome.

All of that said, the Pan Am is most suitably mated to cans of more than 60Ω. It prefers headphones whose efficiency rating is 86-106dB. It all depends on what headphone you are using, though, and even on the valve set you plug in. Whatever set you use, favourites such as the Beyerdynamic DT880 600Ω, the Audeze LCD-2 and 3, and a slew of Sennheiser’s top headphones will sound just perfect. HD600/650/700/800. Done, done, done, and done.

With the above headphones, the Pan Am’s full character gets the chance to play. That character is an interesting mix of ALO’s house sound. Partly governed by the wilder, warmer Continental lineage, partly governed by the controlled, detailed sound of The National, the Pan Am pays homage to its older siblings at every turn.

By ‘play’, I mean that the Pan Am goes ‘boom!’ in the lower bass. That is, if it is paired with high Ω headphones. Headphones of over 300Ω, or otherwise insensitive headphones show almost no load to the amp and therefore go ‘boom!’ the most. It is a pleasant, but noticeable upturn in the range of 20Hz to about 100Hz. Earphones, on the other hand, are the complete opposite. Whether low or high Ω, super-sensitive or not, you will get massive bass drop off. The best pair for the Pan Am is the Etymotic ER4s which suffers the least bass drop off.

Gain on the Pan Am is semi-aggressive, the difference between low and high being roughly 6dB. The great news is that if you bump it accidentally, you won’t bust your ear drums even if you have sensitive earphones plugged in. But, gain is implemented almost perfectly to reflect the limits of what the Pan Am is able to deliver. And folks, it delivers a LOT.

Power here needs to be redefined. The Pan Am delivers power to low-sensitivity, high Ω headphones that belies its price/size/Bender face. Even when fed from the comparatively weak line out of an iPod touch, the DT880 600Ω are completely rocked out. I say this with some sickness in my stomach because I forced my Beybies (get it?) through horrible trials. I maxed out the volume. On high gain. Ouch.

What they gave back was nothing short of astonishing. No phase errors. No crackling. Through the Pan Am, the DT880 600Ω perform like desktop speakers, not headphones. Damn. Of course, at such volumes, my ears would break. For the few short minutes I tortured my Beybies, I stayed safely away from my headphones. I had to. There was simply too much volume. And it wasn’t just a lot of volume, it was high quality volume. Absolutely no distortion. The more expensive (and larger) Centrance DACmini isn’t capable of delivering such power to the same headphones. No way.

For its part, the Audeze LCD-2 is put in its place. It simply can’t overcome the powerful little Pan Am. With new recordings I generally listen to the DT880 at about 9:40 – 11:00 on the volume pot. THe Audeze LCD-2 hovered near that mark. That’s low gain. My ES10 hovers about 5 minutes past the minimum setting. Earphones work well with 2-5 minutes thanks to the excellent volume pot balance.

Stereo separation is quite typical of valve amplifiers, topping out at about 65dB. What’s nice is its rather flat curve. Bass, mids, and highs, each, are tidy. Some valve amps lump bass and low mids together in what amounts to ‘warmth’ and ‘intimacy’ at best, and ‘muddy’ at worst. Assuming you are using high Ω headphones, the Pan Am glides through left/right separation. Unnecessary channel bleed never occurs. Of course, as a valve amp, stereo image is closer than it is in a typical solid state amplifier.

Distortion is one of the specialties of a valve amp and the Pan Am doesn’t disappoint. Depending on what valve set you use, distortion ranges from moderate to high, but the effect isn’t gamey. I’ve found that the Pan Am really straddles the mid ground between the tight sound of The National and the looser sound of the Continental. Its warmth is cued toward smoothness rather than atmosphere. In this regard, it reminds me a little of the Porta Tube+.

Output impedance is obviously rather high. I have not measured it though, as I have not yet invested in a multimeter. Headphones like the DT880 250 or 600 present themselves essentially as no load while headphones like the Audio Technica ES7 present medium loads. Obviously, the Pan Am is most comfortable with the DT880, though headphones with similar spec to the ES7 still sound great. Considering its size, and that it has cute valves poking through the top, the Pan Am is obviously geared toward full-size headphones and desktop listening. The Pan Am is quickly becoming a favourite of mine when paired with the DT880. But, when using earphones, I am left with one thought: where’s the bass? The image isn’t congested, which is a blessing. Generally congesting comes from channel bleed and the collapse of the high midrange in the face of an overbearing bass. Well, with earphones, bass collapses. What’s left is midrange and an interesting and chaotic high range shelf. Shame. Since there is so little noise and since the output is already almost perfectly balanced at low volumes, I wish that this amp had the low Ω output of the Porta Tube+. It would be the perfect do-it-all amp.

If you would like to read more about the performance of the Pan Am, head to our forums where RMAA benchmarks and square waves have been uploaded. (NOTE: these will be uploaded in the next 24 hours.)

On the valves
I’ve not decided on a favourite valve set yet. Each offers plusses and minuses. The Chinese set offers higher output volume, decent stability with low Ω earphones, and a certain ‘wild’ character that is half the fun of valve amps. Think Woo Audio 3. The German valve set is more laid back and at its best with high Ω headphones. Overall, it probably performs the worst, but is nice to listen to. The Russian valve set really rides the line between the Chinese and German sets. It has the same excellent left/right balance of the Chinese set and sports a more laid back, performance-by-the-numbers sound. But, like the Siemens set, it is less susceptible to outside outside interference. Overall, its performance is best across the board. Looking over the last month, I can say firmly that I’ve used the Russian valves most often.

Ahem, the Russian set may be my favourite.

Unfortunately, there are a few issues with the Pan Am. First and foremost to an iDevice user is that Jailbreaked or no, no iDevice can currently power the DAC. If you want to keep the Pan Am and its companions small, the best you can do is a netbook. But, that’s almost par for the course. About half the USB DAC units I try require too much power from the USB port. Ho hum.

1. Interference from external mains sources can be intense when using low Ω headphones and earphones. Particularly, interference comes into play when using the Pan Am around laptops. Typing away, your palms and your lappy’s keyboard will form a small electric circuit, causing a small ground loop even when connected to the Passport. The Pan Am will hum. Humming is ameliorated by keeping your hands away from mains-sucking devices.

The front plate also conducts electricity, so if you have a habit of cuddling your amps, you’ll have to adapt. The good news is that this ground loop is inaudible via high Ω headphones such as the DT880, HD600 and LCD-2, and nearly so via headphones such as the Audio Technica ES10.

2. USB input quality isn’t the best. I think that most of us are used to USB DACs that under-perform, particularly in portable amps. Perhaps it’s the proximity of the DAC and the power input, I don’t know. If I were big into USB audio, I’d probably consider this an Achilles heel to what is otherwise a very fine amplifier.

3. High Ω output is an issue that is finally making it to the lips of the regular Joe and Joeette at Headfi, particularly as it applies to portable headphone amplifiers. Portable headphone amplifiers need to be able to power very difficult to drive multiple armature earphones. If their output impedance is too high, they can’t supply enough current to sustain clean, non-distortive signals at any volume. Well, the Pan Am isn’t able to drive those earphones very well at all. It does an overall good/decent job with the likes of the ES7 and ES10 and maxes its performance with headphones in the same class as the DT880/HD600/LCD-2. But earphones aren’t its forte.

Why I write this issue last is that it is somewhat ameliorated by the fact that the Pan Am is a desktop amp. It isn’t meant to be pushed into a pocket (though it may fit into a purse). Generally, it won’t be paired with the likes of the Earsonics SM2. It will be paired with headphones that actually sound good with it. So, while I wish ALO had implemented a lower Ω output, I don’t think it’s necessary for the current design. What it means is that owners of low Ω headphones will not hear the Pan Am in all its glory. And that is a shame.

I’ve seldom been this excited about a headphone amp. I can’t even follow up the last sentence with “once you’ve seen one-” for one simple reason: I’ve never seen a headphone amp like the Pan Am. It is part portable, part desktop, all modular, and as powerful as hell. I almost expect it to walk off my desk and guzzle down a case of Grand Kirin, yelling “kiss my shiny metal ass!” punching a hole in this shoddy Japanese apartment on its way out. It’s an amp that the competition won’t forget. Nor will its customers. Stack it, pack it, snap it together. Plug it in and take it out. As long as you have the right headphones, the Pan Am is the most clever sub 1000$ amplifier out there, bar none. Its few issues aren’t small, but they are overshadowed by a fantastic feature set that overall, screams: “Grab my shiny metal ass!”

Easy to use
Goes with you
Extremely powerful output
Rollable valves

Case conductivity
High output impedance
So-so USB DAC performance and not iDevice compatible

Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

Read more]]> 3
ALO Continental V2 headphone amplifier in review Sun, 09 Sep 2012 23:45:37 +0000 I have high blood pressure. I get excited easily. For my weight and height, I have a large bum. Fortunately, after applying minus 6 and minus 5 contacts to my eyes, my vision is good – I can tell a masterpiece when I see it. I’m certainly not one. The ALO National is. But for … Read more]]>

I have high blood pressure. I get excited easily. For my weight and height, I have a large bum. Fortunately, after applying minus 6 and minus 5 contacts to my eyes, my vision is good – I can tell a masterpiece when I see it. I’m certainly not one. The ALO National is. But for the mistake of ending early, so is its forebear: the Continental V1 nearly is, too. The Continental V2 makes the grade, too. It shares most of The National’s good stuff and brings to the table a sound all its own.

Dimensions: 2.32 x 3.89 x 0.56
Battery Play Time: 7-8 hours
Battery Recharge Time: 3 hours
Frequency Response : +/- 1 dB:40Hz-20KHz
Input Impedance: 30KOhms
Maximum Input Level: 5VRMS
Channel Tracking: < +/- 0.2dB
Maximum Output: 20 V Peak to Peak
THD+N: 1%

Contact ALO
1810 SE 10th Ave. Unit B
Portland, OR 97214
Phone: +1 (971) 279-4357

ALO-ContinentalV2-accessories ALO-ContinentalV2-box ALO-ContinentalV2-DT880 ALO-ContinentalV2-glamour ALO-ContinentalV2-in-box ALO-ContinentalV2-rubbers Continental dominating a Stack with CLAS and MyST 1866

This review is TMA’s third glut of grammatical errors and mug shots dedicated to valve amps. The first detailed Woo Audio’s WA3, and gushed on and on about craftsmanship and a sound that is decidedly ‘tubey’. The second, detailed the GoVibe Porta Tube+, and waxed lyrical on about beautiful highs, buttery smooth transitions, but waxed cynical about its itchy workmanship.

The Continental V2 is every bit the feat of engineering that the Woo Audio WA3 is, though it runs from batteries, not the mains. Its guts, rather than being strung point-point, lay soldered into silicon. It is solid, beautiful, ergonomic, and a pleasure to use in every turn of its volume pot, in every flip of its volume lever.

And, most important of all, its voice effuses the same lush, rich midrange, the same delicate highs. Woohoo!

Build Quality
Because The National and the Continental V2 are – practically and wonderfully constructed – two peas in a pod, I’m tempted to copy and paste test from The National review here for reference.

There is very little that distinguishes one from another in quality of build. The Continental V2 inherits every one of The National’s good points.

On the outside, the differences are nill. For the sake of brevity, you can read my gushings here. For the sake of thoroughness, however, the differences, where evident, will go down here.

The most obvious comes in fifteen tiny holes sunk into the amps’ brow and temple, just above the valve. These help ventilate hot air coming from the valve. The Continental V2′s guts sit in a smaller chassis than Porta Tube+ guts do, and are sewn in tightly. They need all the ventilation they can get as the Continental V2 gets quite warm.

One reason the guts are sewn in so tightly is that ALO followed Apple’s lead and have glued the battery into the V2′s chassis. Thus, the battery isn’t user replaceable. If by chance the battery should perish, ALO will replace it for you. But you, armed even with the most ferocious of spatulas and pick axes, will not get it out yourself without damaging the spatula, and perhaps the pick axe. The Continental will be reduced to a resume of interesting parts and aluminium shavings. You won’t be able to check the circuit board, either, without breaking the seal. The Continental’s guts, my friends, are tucked safely (and very securly) into their skeleton.

Apart from that, both The National and the Continental V2 share the same thick, scratch-resistant aluminium chassis and are built to the highest standards possible.

Ergonomics and Polish
Again, I’m tempted to copy and paste my ramblings from The National review. Instead, I’ll let you read it on your own.

Overall, nothing drastic has changed. The same perfect spacing, wonderful volume pot, easy-to-engage gain, the same perfectly lit lamp – all there. The Continental V2 is all that The National is, and a bit more. Bigger that is. It’s about 1 centimetre longer front to back. But for a bit of paint advertising ALO’s website, the front and back plates are virtually identical, too.

The difference – and my wife feels this is no small thing (and it isn’t – it’s huge) – is the brand font. Yes, folks, I’m going to yammer on about a font… in an amp review.

I’m with my wife here and much prefer The National’s tastefully off-centre, newspaperesque script. It’s less geeky, more metro, and utterly attractive. The Contintenal’s font is classy, but it’s the Masonic ALO badge that has me hiding the entire amp in an Apple Sock.


That’s just my interpretation of polish.

Let’s get back to ergonomics. Like I said, there’s not much between the two amps. They’re siblings through and through. Hot siblings. The National dissipates quite a bit of heat for a solid state headphone amp. The Continental V2 dissipates quite a bit more. So much more in fact, that I can’t recommend stuffing it in your pocket in a Japanese summer.

I did that on my way sweaty way to immigration.

Damn near electrocuted myself.

Again, nothing new here. Both the National and Continental are straightforward amps. Plug in your source, your phones, adjust the gain, the volume, and enjoy. And, assuming you enjoy rich, lush sound, you will enjoy.

Under the bonnet is the Continental’s magic, a tiny, low-voltage valve and a sound that fits the description. The volume pot is wonderfully balanced, and its low gain setting fits most highly sensitive earphones just fine.

Here, I’m not tempted to copy and paste. The sonic differences between the National and Continental are evident from the first listen. Still, I think you will agree with me that ALO have begun to develop what I think is a nice house sound, though between The National, Continental, and Rx brands, there are important differences.

Valves amps take time to wake up – and sleep. Portable amps are no different. The Porta Tube+ goes from silence to full sound in about ten seconds. The Continental takes about 12-15 seconds longer. Turn it off, and music drifts out in the same manner. It’s like pins and needles, but much more fun.

Then, there is power. Both amps spit out enough voltage to get almost any headphone to ear-splitting levels, though their approach is different.

With headphones and earphones that present small loads, say over 40Ω, the Continental will give quite a bit of extra low end rumble. With no load, that peak, which starts pretty much at 20Hz and goes to about 120Hz, is even bigger. It’s very interesting, and for people that consider cans like the DT880, K701, and K550 to be bass shy, this low end hump could be a godsend. Also interesting is the placement of this small, but discernible hump. It isn’t in the mid-bass (the frequency slot that most people call bass). No, it’s in the proper bass.

This amp raises that frequency band by up to three decibels. But even if ALO were to have raised it by 8 or so decibels, they would still have obviated boom and bloom that occurs from raising the mid bass. Just a reminder: extreme frequencies tend to border on inaudibility. But, this hump is discernible – if your music has that information to begin with, and if your headphones aren’t severely rolled-off to begin with – though just.

Interestingly enough, that same bass (sub-bass to help the younger generation) isn’t held up when using headphones of less than 40Ω. The amp becomes a different beast with low Ω headphones. Most presence is shifted to the high-mids. Both bass and high treble dynamic presentation is softened.

Which I am fine with. Here’s why:

Though the Continental II is a portable amp, it is probably best suited to desktop-replacement work, where it will drive highΩ headphones that value its voltage.

And regarding size, the Continental II is just longer than The National, weighing just a bit more. But as I said before, it gets warm – quite warm. The National lit a small fire in the pocket. The Continental should probably stay out of the pocket to begin with! It does get warm. The breathing holes are there for a reason. Keep them clear. In my month or so of use, I’ve found that I tend to use it most near my computer, or on my sofa almost always plugged into my DT880 600Ω which is basically made for it.

Besides the above-mentioned bass bump, the Continental II has that telltale valve sound – warmish, with a dry (like wine, not humour) lower midrange. On a valve scale, it is more Woo Audio 3 than Porta Tube+. In fact, the differences between Jaben’s and ALO’s amps are stark. Jaben’s amp is loved for its extended but smooth high range, while the Continental is loved for its well-resolved midrange, warmth, and slightly elevated bass. Both are valve amps, but in sound signature, the two are very different.

Their similarities are the similarities that nearly all valve amps have: high distortion. That distortion smooths out little niggles in bad recordings, and tames some screechy headphones. Smooth really is the name of the game. In Japan, both amps have drawn comparisons, and some people have decided there isn’t enough difference to make a decision, while others prefer one or the other for a certain reason.

The Continental outputs a tad less background hiss than the Porta Tube+ and sports the necessary (as this amp is powerful) gain switch on the outside of the amp. Jaben requires you to undo the front plate, get out your eyebrow tweezers and replace jumpers.

I find the Continental II to be clearer in the bass while the Porta Tube+ is clearer in the upper mids (hence, maybe, the reason I fell in love with its high mids). They are similarly congested in the highs, but again, that congestion is comfortable. Overall, for a warm tubey sound, the Continental II is a better buy. For a slightly clearer, but more solid state sound, the Porta Tube+ is better. Other decisions should be made on the headphones you want to use, and on build quality.

Remember, the Continental is more at home with full size headphones and portable phones with impedances of more than 40Ω. The Porta Tube+ is equally comfortable with low or high Ω loads.

Sound in a Nutshell
Smooth out The National’s highs and upper mids a bit, add an emphasis to extreme lows, and some of that good ol’ valve distortion and you have the Continental II. There really is a family resemblance to the two. It is amazing. The Continental II also has less background noise, but with low Ω headphones and earphones, it is also less dynamic. If you are primarily using earphones, I suggest staying with The National, which will give you harder hitting lows and a more exciting upper midrange.

But, if you are out for the warm, lush valve sound and use headphones of more than 40Ω, I can’t recommend the Continental II enough. It really is the most characteristically tubey amp I’ve heard. Ever. Woo Audio 3 in your pocket. Tell that to your friends.

RMAA scores
For those interested in seeing RMAA scores, go here.

Scaling with better sources
As with most good amplifiers, you will get more power from this amp with higher quality/more powerful input. The CLAS is a source that will really up the output power. Fortunately, the volume pot behaves well even when hooked up to line-level sources. With full-size headphones, it is perfectly matched with a good HiFi or CD player.

In fact, I recently attached a Hifiman HE5 to the Continental II and was surprised by the power and control in the combination. Again, I listen to lower volumes and have no intention of bursting my eardrums for reviews. I listen to enjoy my music, not break my biology.

Best headphones for the Continental II
As long as you have a somewhat sensitive headphone, even 600Ω is chicken pie. The DT880 600Ω goes with high gain to about 88% of the volume scale with no phase errors or other telltale signs of distortion.

My Audio Technica ES10 is also another wonderful combo headphone that fits the Continental’s nature. I have a feeling that if you find your headphone to be ‘sibilant’ or harsh, the Continental may well be the amp for you. I’ve heard it said that even warm headphones such as the Sennheiser HD60 ( shares good synergy with this amp.

My only issue with the Continental II is that it doesn’t play nice with low Ω earphones. It’s definitely audible. The amp has wonderful bass and wonderful highs, but with low Ω earphones, you will get an upper-mid centric amp that isn’t excessively detailed. The output impedance seems too high. Plug in a pair of ES7 headphones to it and the National, both matched to the same out line volume and the ES7 is quieter and less dynamic on the Continental II.

Which is a shame because otherwise, this amp is the sliced bread among portable valve amps.

What’s the conclusion?
Let’s face it, ALO are one of the masters of portable headphone amplifiers. Not a one lacks sufficient power, nor good looks, nor build quality. And as I said above, there is a definite house sound developing, and overall, that sound is great. The Continental II has a very low noise floor, excellent ergonomics and build, good low end kick, and great balance. If it were not for the fact that low Ω earphones sound congested in comparison to proper headphones – this is, after all, a portable amplifier – I would consider this the king among ALO’s amp line. Mated with the DT880 (250 or 600), the T1, T70, HD600, K701/2, K550, etc., it is one of the most soothing, beautiful sounding portable amps out there. With 7-8 hours of battery life, you can forgo the mains for your home rig, and pack in an entire day (or night) of music loving. For headphone users, I consider it a must-have amp. Fit it in your bedside rig, your HiFi, your TV rig – anything. Because it really can sing.

Like a WA3 in your pocket
Warm, smooth sound
Extra low end for high Ω headphones
Excellent ergonomics
Excellent build quality

Gets hot
Low Ω earphones change the sound of this amp

Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

Read more]]> 0
Audiophile Friday #1: Cypher Labs Algorhythm SOLO vs Venturecraft Go-DAP Unit 4.0 – Digital Output Sat, 19 May 2012 05:22:45 +0000 Last week I half-arsedly introduced two accessories made specifically for the iDevice audiophile, the Venturecraft Go-DAP Unit 4.0 and the Cypher Labs AlgoRhythm Solo. Both are able and willing to replace larger, more expensive and decidedly untransportable HiFi gear, but only one is worthy of doing so. What’s important Each decodes information internally, outputting high … Read more]]>

Last week I half-arsedly introduced two accessories made specifically for the iDevice audiophile, the Venturecraft Go-DAP Unit 4.0 and the Cypher Labs AlgoRhythm Solo. Both are able and willing to replace larger, more expensive and decidedly untransportable HiFi gear, but only one is worthy of doing so.

What’s important
Each decodes information internally, outputting high quality analogue signals. But, neither stops there. Venturecraft’s Unit 4.0 spits out SPDIF over a 3,5mm optical connection. It also protects your iPhone, charges it, and syncs it via a cheap and ubiquitous a mini-USB cable. Remember the original Go-DAP? This is its younger, more capable sibling.

The Solo won’t charge your battery nor protect your iPhone. It’s actually sort of beastly to lug around. But, its glory isn’t its general utility. Its glory is its sound and signal quality. Since it doesn’t harness an internal headphone amp, it spits analogue signal at line-level and SPDIF digital signal over coaxial. It pairs perfectly with the likes of the ALO The National and ALO Rx and many other headphone amps.


Why digital?
For years, we’ve had access to the rather high-quality line outputs of the iDevice. Via 30-pin cables, we’ve been able to hook up high quality portable amps, recording devices, microphones, and sync cables. Then came the Wadia iTransport, a device that sat on your desktop and allowed your iDevice to spit out digital signal to an external DAC. Now, there is a host of such devices.

They why of digital is fairly easy to decipher in a single word: accuracy. While analogue signals sound great, they are prone to distortion, jitter, noise, and theoretically degrade via poor quality cables.

Digital has its own host of problems, but for the sake of brevity, I’ll skip them. The music in your iPod/iPhone is 100% digital. The aim of both the Go-DAP and the SOLO is to keep that signal digital. The Cirrus Logic chips in the iPhone/iPod do a fine job of converting digital signals to analogue, but they can be bettered by external converters.

In the case of the SOLO, they are completely outclassed.

The effects
Here’s where the argument rights itself a bit. Since the iDevice already does a fine job of converting digital to analogue, DAC virgins and indeed DAC party girls and guys may not immediately realise the effects. What you pay for is the last few iotas of quality, not a revolution.

However, if you pair your iPhone with the proper outboard amps, you can get both demonstrable and measurable improvement.

Digital signals from both the Go-DAP and the SOLO can be split into balanced signals given the right outboard DAC. Balanced signals in turn, can be read by the proper amp, and plugged into the proper headphone. Balanced headphones are few and far between simply because most require rewiring. Some headphones such as new AKG and Sennheiser models can be paired up with high quality balanced cables without surgery. Some IEMs can, too, but IEM topology, whose balanced armature crossovers are meant to operate differently. Some may indeed be better balanced, but among those that sport passive crossovers, I’ve yet to discover one that retains its original magic.

Single driver headphones are another matter all together. The rather thrifty Einar balanced amp provided more power to the DT880 and better left to right stereo separation. The effect was immediately recognisable at matched volume levels.

If you want to get into the more powerful, higher-end world of balanced headphones or speakers, but want to stay portable, either the Go-DAP Unit 4.0 or the SOLO is your ticket.

Signal tests
This review’s RMAA measurements reflect the performance differences between the Venturecraft Go-DAP Unit 4.0 and the Cypher Labs Algorhythm SOLO. Since these measurements are taken with my equipment, they should not directly be compared measurement-to-measurement to other technical data taken with different equipment. The data represent the ability of the amplification circuit to drive headphones and speakers.

Frequency response
As you can see, the SOLO is flawless. In digital, there is zero deviation from RMAA’s benchmark. You cannot do better.

SOLO: win

The Venturecraft Unit 4.0 takes a different approach to playback, which is to roll off the highs from just after 1000Hz. It is an extreme approach that isn’t the effect of load. Unloaded, in both digital and analogue, the Unit 4.0 is unable to sustain anything resembling a proper signal. Because audio is subjective, such a result isn’t a disaster. Many audio makers add their own signature to sound. Personally, I enjoy the sound very much, especially with the likes of the DT880, which are bright to begin with. However, a digital signal should be as close to the original signal as possible, and in this case, it isn’t.

Go-DAP: fail

Noise levels
Again, the SOLO sweeps the test. Its noise levels top actually surpass the limits of 16-bit audio at -97,9 decibels. You won’t find better performance in any portable device, and even in home units, higher scores are probably not discernable. When spitting out analogue, noise creeps in and averages -93,1 decibels, again a damn fine score.

SOLO: win

The Unit 4.0 fairs well at -94,2 in digital. It doesn’t break the 16-bit barrier, but the difference in digital signals between the two is negligible when feeding outboard DAC units. In analogue, the Unit 4.0 falls to -87,3 decibels. Again, it is a respectable score, but not necessarily so when considering that the iDevice is able to sustain loaded levels up to -91 decibels.

Go-DAP: win

Dynamic Range
Again, the SOLO exceeds the bounds of 16-bit audio at +96,7 decibels. One wonders how it would fair if playing back higher resolution material. The DAC is capable of it, but the iPhone isn’t.

SOLO: win

The Go-DAP still isn’t putting its strong foot forward. At an averaged +63,3 decibels, it puts out the dynamic range of an iPod under heavy load. It actually sounds decent here though, quite excellent for recordings that are heavy on binaural material and harsher sounds.

Go-DAP: fail

THD IMD and noise
If there was a more violent trounce party, I don’t know what it is. The SOLO isn’t able to manage the bounds of 16-bit audio for THD+noise, but it does deliver very high quality signal.

SOLO: win

The Go-DAP sprouts IMD errors from its digital ports like the Titanic spouted water into the Atlantic Ocean. Its analogue output fairs much better, managing merely the worst output score I’ve tested thus far. The digital output is simple astonishing.

Go-DAP: fail

Stereo separation
Here, both units perform well within the bounds of my expectation. I’ve found that the original RMAA signal played end to end from other digital outputs never deviates from around -50dB at worst. Why, I can’t tell you, but: both units perform horribly here.

SOLO: fail
Go-DAP: fail

Digital output was flawless. This is the analogue wave.

Square waves
Analogue: both units perform well here, with slight ringing in the high frequencies the sort of low frequency responses you would typically see in high quality analogue devices. Ringing is minimal, though, again, the SOLO outperforms the Go-DAP Unit 4.0. I would suggest that the differences that favour the SOLO aren’t discernible.

Digital: both units perform well, but the SOLO is less plagued by ringing. The Unit 4.0 shows slight, though almost imperceptible ringing in both signal extremes.

SOLO: win
Go-DAP: win

NOTE: Take note of the shape and size of the ringing portion. The Square waves are drawn by Sound Studio when recorded in/out via Edirol FA-66. The software doesn’t allow for 100% scale comparisons.

As you can see, the SOLO ran digital circles around the Unit 4.0 in just about every test. Add to that a cleaner analogue signal, and you have a truly pocketable reference level system. Of course, the SOLO necessitates the use of external cables, amps, and a lot more money. It exceeds the bounds of 16-bit in every test but one: stereo separation, and creates a perfect square wave. In its singular purpose, it is nonpareil.

The Unit 4.0 is an amazing device. It charges. It protects. It amps. It spits digital. But, apart from its incredible ability to recharge your iDevice, it does so with a lot of strain. Since it is heavy, a fall to the floor will likely damage it. Its amp is fun, and loud, but has more signal noise and distortion than any iDevice does. Its digital signal is a wonderful accessory that adds functionality to your HiFi, but it isn’t nearly up to the same quality as the SOLO is.

If Venturecraft can fix this with a firmware update, or simply by choosing a more stable DAC, they should do so. For now, SPDIF output seems at best a lazy implementation.

Of course the Go-DAP costs less, charges and syncs syncs, and keeps cables out of the way. There is none like it. And, in case you want to ditch the charging features, Venturecraft have just introduced their next project, the X which acts as a DAC and amp for your iPhone and your computer. Again, it is the first of its kind. Get ready for myriad copycats.

On the Go
This light-hearted audiophile would choose the Go-DAP simply because it charges and has fewer parts to break. Cables are buggers. The SOLO practically requires a case of some sort to keep everything together. And, when packed with an amp, headphones, and all the interconnects you need, it looks like a bomb.

Still, both have their fans. I saw heaps of SOLO stacks at the recent Fujiya-AVIC headphone festival. People use them. People enjoy them. And those people are audiophiles that demand the utmost quality from their portable listening rigs.

Both units work with just about every recent iDevice. The SOLO is just that much more compatible. I’ve had a bugger of a time getting an iPod touch 4G working with the Unit 4.0. The SOLO worked with every 30-pin iDevice I plugged it to.

The Cypher Labs National stack – not an easy carry

Why iDevice and external DAC?
Here’s a question I’m sure is asked by many audiophiles who look at devices such as the iBasso DX100, HiFiman, Colorfly C4, etc, and suffer indecision. The simple answer is this: if your music requires gapless playback, perfect navigation, few to no firmware issues, better battery life, and almost no build quality concerns, stick with Apple.

If you want the absolute best, you will have to purchase external DACs/amp for these players anyway. Of course, if you hate Apple, you are probably not reading this article anyway.

I throw music onto my iDevices via iTunes drag and drop. I don’t want to make CUE sheets, worry about WAV compatibility, or poor battery life. I don’t suffer players that can’t play back gapless files. Since I demand that music plays back as simply in my device the same as it does from a CD, there is only Apple.

After nearly 2000 words, my conclusion is very simple, but it hinges on you. If you value compactness and have an iPhone 4/s, there is NO other choice than the Go-DAP Unit 4.0. You still get digital output and fun/powerful sound plus all the other features. The Go-DAP Unit 4.0 is a great device. But, its compromises in output signal quality are severe.

Between the two, the SOLO is the only choice for reference-quality sound. But it gives up is portability. It also requires you to invest in outboard audio components. But then again, you knew that, and you were prepared to invest. To you, only one thing matters: signal quality.

While this seems a lopsided comparison, it is the only sort that is possible. Venturecraft chose to attack all angles, Cypher Labs chose to tackle one. Audio-wise, only one nailed it. That is the Cypher Labs AlgoRhythm SOLO.

Cypher Labs
Cypher Labs LLC

4260 Galewood St. Suite B
Lake Oswego, OR 97035

Umeda 1-2-2-1400
Kita-ku, Osaka-shi
Osaka 530-0001
SOLO-GoDAP4.0-ct SOLO-GoDAP4.0-dr SOLO-GoDAP4.0-fr SOLO-GoDAP4.0-imd SOLO-GoDAP4.0-ns SOLO-GoDAP4.0-thd The Cypher Labs National stack - not an easy carry CLAS-COAX-SPDIF VCGo-DAP4.0-SPDIF CLAS-VCGo-DAP4.0-stack.2 CLAS-VCGo-DAP4.0-SPDIF.2 50SQ-SOLO-vs-GoDAP-4.0Read more]]> 3
ALO The National headphone amplifier in review – a new class Mon, 14 May 2012 00:59:42 +0000 After having created perfection in the Rx, ALO are free to experiment. Their first experiment, The Continental, is quite a hit, especially as it packs valves under the bonnet for a truly classical sort of listen. But as ALO explain, the use of limited valves means that the Continental has a shorter time on this … Read more]]>

Handsome and powerful - and compact

After having created perfection in the Rx, ALO are free to experiment. Their first experiment, The Continental, is quite a hit, especially as it packs valves under the bonnet for a truly classical sort of listen. But as ALO explain, the use of limited valves means that the Continental has a shorter time on this planet. Enter The National, an amp that they reckon is the answer to the Continental. I can tell you right now: The National is a single box that can fill the void of both portable and living room headphone amp.

Frequency response: +/- 1 dB:10-100,000 Hz
Maximum Output: 20 V Peak to Peak
THD+N: 0.004% @ 16V Peak to Peak out into 600
Broadband Noise: : < Input Impedance: 10KOhms
Maximum Input Level: 3.5VRMS
Channel Tracking: < +/- Battery life ~ 15-20 hours

ALO love big batteries

Build Quality
There’s hardly an amp out there that isn’t made of solid metal. Most are held together with iron or steel bolts and display their guts on green boards. The National is no different. Well, that is until you scratch the surface. (Still not sure if that pun was intentional or not.)

Every port, every bolt, every switch sits in countersunk wells. The only plastic nub on the amp is the high/low gain switch, which sits in a veritable castle of a well. Strong o-rings guard the in and out ports. So don’t worry. Fat, heavy headphone plugs can be used with abandon as this amp is a tank. The National is is mottled, invoking little fear of scratching.

The National’s logic board has a cut-out to fit a large battery. Hence, the battery rattles around a little in its niche. If the rattling annoys you, wrap the battery with a few thin elastic bands. (A braver man can steal his wife’s foundation sponge and force it in. I’m making no suggestions here.) The upside to this is that changing the battery is easy as it isn’t held on by unnecessary adhesives. Also, there is less chance of a bad battery frying nearby components.

The only feeble component is the 12V mains adapter whose male bits don’t securely fill the female bits. I broke my old Atari Lynx female bit with a real needle of a male bit. I was 13 years old.

The ALO is a grown-ups’ amp. Be a smart audiophile and charge your National in a safe place.

Ergonomics and polish
Before you plug in your headphones, glory in the wonderfully spaced in and out ports, the smooth volume pot, the mottled fascia. One-over The National over a few times. The font, by gods! worship it!

I only wish I were a better photographer than I am. The National is hands-down the handsomest portable headphone amp I’ve handled. No line is wasted, no item is out of place. No other amp compares.

This attention to detail is the best evidence I can find that ALO listen to and use the products they design. Let me try a little creative writing to illustrate how well thought-out The National is.

ALO’s Ken Ball is reading a mystery novel late at night on his iPhone. His wife sleeps beside him. Of course he has his favourite Ultrasone headphones plugged in. Peter, Paul and Mary are happily puffing away inside his eardrums. The novel just so happens to have been an iTunes gift, and contrary to the excited praise it received from the self-proclaimed mystery-loving friend who gifted it, it is a bore. After three mind-numbingly awful chapters, Ken shrugs his iPhone to his nightstand and and the room goes dark. But upset at wasting his time with the novel, he keeps The National on. He just needs more Peter, Paul and Mary. This Land is Your Land washes over him and he feels better. His wife happily snores beside him in a soft darkness till visions of the Magic Dragon overtake him. Not once does the glow from The National’s power lamp bother him.

Friends, this amp is great for use at a bedside. The lamp is lit just enough to tell you it is on, no more.

In short, I’m still trying to fault The National somewhere. I’ve taken it as a personal quest. The mains adapter isn’t enough. The battery rattle is fixed with a bit of foam. That beautiful font haunts my quest. Give me another sixty years, we’ll have a bedside chat at some hospice or another. I’ll be glad of the company.

Perfect ergonomics

The National is a headphone amplifier, plain and simple. If you want gimmicks, look elsewhere – that is, unless you consider polish a gimmick. From the build of the case to the shape of the logic board to the in and out ports, there is hardly an amp out there that is as ergonomically designed, or as useful for a wide variety of headphones and earphones. Right, there is that cute nubbin of a gain switch. Oh yes, and an easily-swappable battery. And sturdy casing. And excellent left-right balance from the volume pot.

And… and… and…

I’ll see you in sixty years.

Sound quality
Polish and build are great selling points, but in the end, one buys an amp for listening, not ogling. (In fact, I’m not even sure ears can ogle – mine sure can’t.)

If yours can, go ahead. The National sounds great. Indeed, it is one of a handful of amps at this price point is even trying to make itself heard. ALO aren’t playing Toyota, moving the steering wheel a centimetre and calling it a new model for ladies. They aren’t undercutting everyone else’s prices by stooping to the same level of shoddy build. And they’re not rolling off the treble for a ‘rich’, ‘warm’ sound. The National is made to different standards in both build and sound. And that sound is lush in the midrange, and bright and powerful.

High-voiced midrange instruments have a close, intimate sound – an intimacy that isn’t strictly speaking, natural, for solid state amplifiers. That intimacy isn’t a blur, though. There is ample spacing between instruments, just not Rx spacing. The warmth may be the product of a very slight time delay in high-voiced instruments, something that I will for lack of better vocabulary, call a high-range smear. That hint of delay is an part of a sound signature that is built somewhat off of a valve-amp blueprint. I think it will find itself very well thought of in the living room and when paired with achingly treble-tipped earphones.

Now let’s talk space.

There is a lot of it in the low frequencies, no matter the type of headphone it is paired with. It is clean and powerful and taught with lively positioning. Its image is 3D, not wall-of-sound, with a tendency to warm slightly ‘behind’ the ears. In terms of attack and power, The National is in a space much its own. Sub-bass is ever so slightly rolled off, but a powerful emphasis beyond 60Hz, especially when paired with headphones such as the Ultrasone DJ1Pro, is prodigious. Of course, we are talking minutely here. No self-respecting amp would sound that different to the original wave without an external EQ circuit, so the prodigy I refer to is mainly the incredible separation and definition in the low frequencies.

This space continues well into the middle mid tones where instruments thrive in their own space. It is only in the higher mid frequencies that any sort of artefacts appear. As mentioned way above, some of these artefacts are part of ALO’s design. The minute delay is a wonderful effect though hardly audible. It’s a happy shadow cast in most music.

Under heavy load, harmonic distortion artefacts appear, though not enough to cause displeasure. However, if you are a user of complex multi-armature earphones of very high sensitivity and swings to low Ω, you may find that complex orchestral pieces aren’t as articulate as you would like. For you, I would suggest the Rx, which is completely adroit no matter your earphone.

But all of that is esoteric talk. No amplifier sounds completely different to its siblings and competitors. The National doesn’t transform you music into something else. Its primary job: holding signal when driving large and small loads, it does well. And whilst that is going on, The National throws in a bit of its own flavour. Can you blame it?

Regarding driving capabilities, The National is more powerful than an amp its price should be. It generally upholds high quality signal when driving multi-armature earphones, and with voltage-hungry headphones, it sustains distortion-free signals even at intense volumes. I am a Beyerdynamic DT880 lover. My DT880 have 600Ω under their bonnets of mesh and steel. Plug them into an iPhone and older recordings are dead, soft, indistinct, and boring. Why? The iPhone hasn’t enough voltage to supply volume for an engaging listen.

With newer recordings, the DT880 can get to good volumes from an iPhone, some in fact, too loud. But, press those recordings to volumes of over 90% (which are necessary) and the iPhone’s in-built amp begins to distort. Not so The National. All the way till 95%, its signal is full, engaging, and fierce. Too fierce, in fact, for comfortable listening. I keep the volume pot at 60% or under in low gain with the DT880, and even at that seemingly tame volume level, I’m probably doing my ears no favours.

More impressive is the pairing of The National and Audio Technica’s ES10, a headphone that can easily cause phase distortion when paired with lesser amps and driven at loud volumes. Plug it into The National and suddenly I feel sorry for it. I can crank The National’s volume pot to 90, to 100% even, and only the faintest hint of sizzle comes from the drivers. It’s a tough life for a portable headphone.

What if you’ve got a nice home system? Or you have a Cypher Labs Agorhythm Solo, or a Fostex HP-P1? How bout a nice home CD player? You are in luck. The National scales up to higher input levels perfectly. Though it will power the DT880 to dangerous levels when fed by an iPhone, a proper line-level system allows The National to reveal even more power.

Charts Disclaimer
This review’s RMAA measurements reflect the performance differences between the naked iPod touch 4G and the same iPod when paired with The National and ALO’s own line out cables. Since these measurements are taken with my equipment, they should not directly be compared measurement-to-measurement to other technical data taken with different equipment. The data represent the ability of the amplification circuit to drive headphones and speakers.

*UPDATE: true side-by-side comparisons will be uploaded this evening. Currently, that data is garbled and the only data available is The National paired with the Cypher Labs SOLO and strapped to the Earsonics SM2, a very difficult-to-drive earphone.

Loaded frequency response
Let’s get onto the boring, objective stuff. Firstly, I would like to tackle The National’s ability to deliver signal both under load and when driving basically nothing. In this case, ‘nothing’ would be something like the Beyerdynamic DT880 600Ω that sucks voltage, but plays nice on amps because of its incredibly high Ω rating and low sensitivity, which induce basically no distortion except on the worst amps.

The National is hardly one of those. As mentioned above, it doesn’t reach the same level of performance as the Rx with all manner of headphones and earphones, but come on, it’s cheaper, and honestly, sounds better with the likes of the DT880. Part of the reason that it distorts with multiple balanced armature earphones is that its output impedance is higher. If an earphone drops below its output impedance when under load, The National will distort.

Just such a one is the Earsonics SM2, which remains the hardest driving universal earphone in my arsenal. As you can see, The National struggles a bit with the SM2. It does no such thing with the Sleek CT7 or the Audio Technica CK100, both multi-armature earphones with relatively low Ω ratings.

However, ‘struggle’ needs reference. RMAA indicates that under the strenuous load of the SM2, mean deviation is far less than a decibel, and exceeds 0,5dB only in the higher frequencies. Such small deviance may or may not be audible. I tend to take the stance that a deviation of around 3-5dB is the lower bounds for audibility.

In short, The National does its job well.

Loaded noise and dynamic range and distortion
Here The National begins to show some of its roots. ALO called on The National to “make the Continental last”. The Continental is a high-end valve amp that many audiophiles are clamouring for. The National, made of more readily available parts, is the answer to a limited Continental. Evidently, ALO had mind to design The National after the Continental – at least to some extent. Valve amps are known to be warmer, smoother, or more temperamental. Discerning audiophiles love valves, especially one unmentionable: distortion.

Let’s be honest here, the whole push forward in digital forged new, low-distortion paths. But since then, truly analogue signal pathways have abounded. Why? People love distortion. It’s warm, it’s fuzzy, and when done right, it can sound nice. Both loaded and unloaded National measurements prove the same thing: there is a small amount of distortion in the signal.

The National almost reaches 91dB of dynamic range. We all know that the dynamic range of 16-bit audio is 96dB, so the mark isn’t far off, but then again, I don’t think Ken was shooting for perfection, he was shooting for sublimation. Perfect benchmark performance is the realm of the Rx; The National is a product with a signature, not a signature product. I may have that backwards, but I don’t see how that matters. This is audiophilia anyway.

91dB of dynamic range gives a good indication in the levels of distortion you may expect from The National.

Loaded and unloaded stereo separation
Overall stereo separation is very good when plugged into most headphones. Again, complex multi-armature earphones cause congestion in the signal. The National favours the upper mids. There is more space and definition in mid range instruments than there is in bass and treble. That said, the difference between all three is small unless you are driving something like the Earsonics SM2. The DT880 600Ω throws no monkey wrenches at The National in any form and both low and mid frequencies are fully clear, detailed and wide.

In wintertime, I can think of no caveats to The National. It’s summer though, so I’ll shoot. It gets warm. I’ve got it in the front pocket of a pair of Asics running trousers. My right leg is sweating. Don’t worry, it’s not enough to burn you, but dear me, The National packs a heating unit in there, too!

I’ll need some company in the hospice. ALO have proved themselves again and I’ve no straws left. No niggles to pick. It its price range, The National is the best I’ve laid hands on. It is also the most interesting. ALO have taken a daring step by designing an amp that has a sound in a price bracket that is devoid of character. The product is almost limitless power for most headphones and ability to scale up with proper sources. In fact, if you were to plunk down 300$ on a single box and call it quits, my recommendation is to go with The National. It fulfils all your portable needs and doubles perfectly as a headphone home amp when fed by powerful sources.

ALO’s precision build and ergonomics are perfect, its sound nearly so, its polish, legendary. The National is defining a class all its own. And now, I must prepare for a long, hard vacation at the hospice. [To anyone, really] you’re welcome to keep me company.

App Summary
Title: ALO The National headphone amplifier Developer: ALO Audio
Reviewed Ver:  Silver Min OS Req: 4.3
Price: 299$-400$
  • extremely powerful output
  • wonderfully detailed, warm sound
  • best in-class built quality
  • oh God! that wonderful font and presentation
  • Price
  • not able to sustain perfect signal under hard loads of complex multi-armature earphones
  • battery wiggles
ALO-National-box ALO-National-CLAS ALO love big batteries ALO-National-in-box Handsome and powerful - and compact ALO-National-SM2-cross ALO-National-SM2-dynamics ALO-National-SM2-fr ALO-National-SM2-imd ALO-National-SM2-imdswept ALO-National-SM2-noise ALO-National-SM2-thd Perfect ergonomicsRead more]]> 3
ALO Rx Portable Headphone Amp in Review – Double the battery, double the fun Tue, 24 Nov 2009 18:12:42 +0000 ALO, a name highly respected for the manufacturing of hi-end audio interconnects and iPod line-out cables has firmly stepped into the world of analogue headphone amplifiers. Already, they have partnered with Red Wine Audio to produce the high-end solid state battery-powered Amphora headphone amp, and now, partnered with GR9 Technologies, are introducing the Rx, which … Read more]]>


ALO, a name highly respected for the manufacturing of hi-end audio interconnects and iPod line-out cables has firmly stepped into the world of analogue headphone amplifiers. Already, they have partnered with Red Wine Audio to produce the high-end solid state battery-powered Amphora headphone amp, and now, partnered with GR9 Technologies, are introducing the Rx, which in their own words, is your ‘prescription for sound’. I say, ‘touché’.

Frequency response: ±1dB; 10Hz – 20kHz ±0.1dB @ 1V out
Maximum output: 7.45V Peak to Peak
Output source impedance: Less than 1Ω
THD+N: 0.004% @ 1V RMS out into 24Ω
Broadband noise: <10μV RMS, unweighted, integrated over 20Hz – 20kHz
Output DC offset: <3mV
Input impedance: 40kΩ
Maximum input level: 5V RMS
Channel tracking (gain difference between channels, all volume steps): <±0.2dB
Gain: 1.5X /6X —5V (switch-selectable), ±<0.5dB
Dimensions: 4.2″ long x 2.5″ thick x 5″ wide

Build and Packaging
“Those who like it, like it a lot!” – if you are not an IPA-drinking Canadian, this quote will mean little to you; but with a certain cache of blogging liberty, and no contempt for Mr. Keith, I will apply it to the Rx. The slim and sleekly-polished palm-sized aluminium chassis says $$$ from the first glance. Make no mistake though, ALO constructed the Rx with one thing in mind: performance. Thus, forget weeny-widget miniaturisation; forget malleable construction – this is a solid, yet surprisingly light machine. Because of its footprint, it fits nicely with an iPhone or iPod touch, but when attached with almost any sort of interconnect, isn’t the compactest of pocket rigs. That isn’t to say that it is big. It isn’t. But, if portable means a matchbox, you may have to look elsewhere.

The Rx’s highly polished surface also attracts fingerprints and unfortunately, scars. When the first scratch scrawls along the Rx’s shiny exterior — trust me, this _will_ happen — it is heart-wrenching. But apart from Apple-esque good, yet scratchable looks, the Rx is a great design. The aluminium walls shield audio from radio interference and do a lovely job in protecting the innards. At the same time, while the Firestone Audio’s products could be thrown through a wall, the ALO remains aloof to violence, preferring to be kept safely on a desk or in a pouch. It’s chassis is strong, but it isn’t bullet proof. And, keeping it beautiful will require an extra step, as the included canvass pouch is about as protective as cooking wrap. But then again, who spends 350$ on a piece of portable equipment only to throw it at a tree? The Rx is a design which will attract certain customer very much, and others, who prefer either smaller, or squarer designs, will probably ‘ooh and ah’ at the shiny exterior, but in the end, move on.

The front of the amp sports all the connections: power, headphone output, and headphone input; and two small blue LEDs indicate if the amp is ON and/or charging. The ON/OFF switch flips easily and the audio ports are spaced perfectly for both large and small interconnect cables. Because the volume and power switches are nestled between the IN/OUT and mains power input, turning the amp on and off and/or changing volume can be difficult. If the power toggle was vertically oriented, this wouldn’t be the case.


For many years, ALO have sported tasteful, if sometimes gaudy designs. No where else is this duality presented better than in the juxtaposition of the Rx’s wholesome packaging to its pimp exterior. It comes safely packaged in an easy-to-open cardboard box which apart from its size, looks like a pizza-box. Pragmatically styled and sized, its design doesn’t spell ‘cute’ as well as Firestone’s does, but it works perfectly.

Features in Review
ALO’s Ken and GR9’s Matt have worked hard to build a great piece of technology. There are literally hundreds if not thousands of portable headphone amps competing for your money and most of them cannibalise the designs put forth by the good Dr. Chu Moy. God knows we don’t need another amp – fortunately, the Rx doesn’t do the same-old in the same way. It employs several exciting technologies which help to distinguish it from its laconic peers. The first is the supervised power/charging circuit which is protects and services dual lithium ion rechargeable batteries which ALO say are good for 24 hours. Ken was adamant about including a dual power supply and Matt drew up the charging circuit which is purported to prolong the life of the lithium batteries. In my giddy stupefaction, I am more excited about is the dual stepped volume attenuator, which to put it bluntly, bloody rocks. Most portable amps use volume pots, or single stepped attenuators which can offer good control and balance, but often, add too much gain between steps. Headphones and earphones are either too loud or too quiet, and amps based on these technology can be cumbersome to use. The Rx, on the other hand, works perfectly with any sort of headphone; and with impeccably balanced left and right channels, maturely steps up and down through volume settings. I haven’t used a better system.

Thanks to its great stepped attenuator, it works well with all interconnects so that the source can be set to optimal volume levels. At my disposal, I have three brilliant line out dock cables: the ALO Cryo and two docks from a small Australian manufacturer, Twisted Cables. But, even a cheapo 3,5 mm headphone mini jack does the trick. Apart from that, the Rx doesn’t hide any extra features. Quite simply, it is an amplifier whose innards are constructed for technically sound and strong audio amplification.

Review-HPA-Rx-Cryo Review-HPA-Rx-TC

Audio Performance
The Rx is among a handful of production headphone amps which output ~1 ohms and can sustain signal for the most demanding of inner earphones to power-hungry headphones. Many amps are rated for 16 or 32 ohms and when faced with the constantly switching impedance of earphones such as the JH13Pro, suffer tumbling audio performance in a variety of audible and measurable criteria.This is where the Rx sings. There simply isn’t a headphone that can stump it; whereas some headphones are made for inner earphones, and others for studio/DJ/home hifi headpones, the Rx maintains an excellent, flat frequency response with every headphone I have thrown at it. But, as with all things, this too has its blessings and curses.

Firstly, the praise. Because of the flat frequency response, no headphone is held back. If the JH13Pro sounded good from an iPod touch, it gains new legs with the Rx; bass texture and speed is improved and the treble which hitherto has alternated from lungy singing to stifled steps is eased. Earphones which employ balanced armatures really stand up with the Rx. Surprisingly, however, the Victor FX500, an earphone which isn’t hard for the iPod touch to drive, is so much better with the Rx. Its highly resolved, chalky bass is even tauter, uncovering new PRaT checkpoints.

Review-HPA-Rx-amped-FX500-FR Review-HPA-Rx-amped-FX500-CT

Where the iPod touch loses neutral response, the Rx picks up. Apart from reaffirming the strengths of the JH13Pro, the Rx reigns in the Sleek Audio CT6 which at times, suffers from a voluble, meandering bass. While it isn’t as precise as the Jerry Harvey’s top end monitor, its acoustically amped bass and treble — my version has ‘+’ treble and bass ports — gain definition and better control. Neither custom monitor suffers any sort of discernible roll-off when driven by the Rx, though, each pick up on of the Rx’s weak points: white noise. It isn’t a big problem, and in fact, the Rx hisses less than a 1st generation iPod Nano. Still, with sensitive earphones, background noise is noticeable as soon as the power switch is engaged. For headphones like the DJ1Pro, Phonak PFE, and to a lesser extent, the v-Jays, the background is perfectly black. The second issue too, only applies to inner earphones. The Rx has ‘ignition thump’; when engaged, its circuitry will thump audibly into the earphones. Fortunately, it isn’t painful, or in comparison to other headphone amps, loud; and headphones can be removed and inserted whilst engaged without any similar adverse affects.

Review-HPA-Rx-amped-JH13Pro-FR Review-HPA-Rx-amped-JH13Pro-CT

No portable amp I have ever used can stand up to the sheer bone-numbing bass and impressively ‘3D’ sound space of a good home headphone amp; there simply isn’t enough gusto in the power supply and output. The Rx, however, does a very good job despite its battery-powered engine. And, even at top volumes, it isn’t over-stretched. At no time do any of my headphones exhibit audible distortion even when driven at peak volumes. And, under hardware tests (as my ears wouldn’t abide it), it is obvious that the Rx doesn’t have a ceiling. In contrast, the Graham Slee Voyager (another expensive portable amplifier) runs out of steam, losing power and signal after its volume pot has been turned to about 80%.

Even the somewhat sensitive DJ1Pro which can accept very powerful input doesn’t distort, and can be driven with aplomb even at the Rx’s full volume. Still, such volumes are unsafe; the message then, is to translate that it is possible to use the amp even at 100%. Continuing with the same headphone, I am surprised by the bass which gains new texture from its drivers when paired with the Rx. It sounds great from the lowly iPod touch, and even from a MacBook Pro, but is much better from the Rx. That headphone, along with a couple of favourites: the Beyerdynamic DT-880 and DT-770, are better with my home amps, but not embarrassingly so.

Review-HPA-Rx-amped-DJ13Pro-FR Review-HPA-Rx-amped-DJ1Pro-CT

Finally, the Rx is an interesting combination of resolution and silk. It introduces very little distortion into any headphone — a fact which makes electronic, dance, and trance listening simple, pure bliss — and produces a grain-free treble. To a certain extent, I could call it smooth. Transitions from low to high are excellent and space is simply stunning. But, where technically smooth, sonically, it is perplexing. Before I get to far here, I will mention that sonically, it is amazing, but with such low levels of distortion, it is mixed bag for certain genres. Distortion can be pleasing – very pleasing. An example is the simple (and cheap) Fireye I which I can recommend based on price and features. Though it lacks a volume pot and hisses loudly, it produces levels of distortion which transform vocal, jazz, and live recordings into simple pleasures. Is it overall a laudable amp? No. But, where the Rx makes no mistakes, it reveals the sonic tendencies in each headphone. If the headphone is grainy, music will be grainy. If it tends to be hot, it will be hot. Perhaps this is an indication of its purity, of its transparency. Still, those who favour distortion will probably reach for a different amp.

The iPod touch 2G, too, is a technical piece of audio kit. Put under pressure, it can outperform almost any other mass-produced portable audio player in nearly every measurable category. But, it doesn’t excel in all music genres. Players like the AMP3 Pro 1 and 2 which aren’t as technically excellent, but harness distortion to their advantage are excellent for jazz, vocal, and even modern rock. My own preferences tend toward tight, controlled, and well-executed sonics though, and I love the combination of the iPod touch and the Rx.

Chart Disclaimer
This review’s RMAA measurements reflect the performance differences between the naked iPod touch 2G and the same iPod when paired with the Rx and ALO Cryo line out dock. Since they are taken with my equipment, they should not be compared to any other person’s or organisation’s technical data. The data represents the ability of the amplification circuit to drive headphones. It is NOT the headphone response data.

Sound conclusioin
Vivid, lively, and powerful, the Rx is a dream among truly portable headphone amplifiers. It literally can drive any headphone from the smallest, most sensitive inner earphone to power-hungry headphones such as the Sennheiser HD-600. Saying that, it outputs optimal pressure to inner earphones and marginally sensitive headphones such as the DJ1Pro. Harder to drive headphones such as the AKG K701 really need a home headphone amplifier, and the Beyerdynammic DT-880, while a smashing companion, requires more beef. For a battery-powered portable, however, the Rx is probably one of the best at any price. Not prone to distort, or roll-off, it presents details and pushes a wide sound stage. Hard-to-drive IEMs such as the JH13Pro are bottomless, layered, and beautiful. But, you must keep in mind that this amp is quite detailed. Nothing smears; nothing bleeds. It has a good, fatigue-free ambience, but if your preferences tend toward the warm and the fuzzy, your search may not be over. Also, there is a low level hiss in the background, and when the power is engaged, a thump.

All in all, this amp is truly a stellar performer, and among battery-powered portable amps, one of the elite.

Buying the ALO Rx isn’t a small decision. At 350$, it sits rather high up the food chain among portable headphone amps. There are more expensive options in the market, but if you are thinking of buying one, you probably won’t be reading this review! What impresses me most about the Rx is that it can drive everything. It thunders past amps which are marketed toward IEMs, and still has the guts to bust up my DJ1Pro, and put on a respectful performance with the HD-600. For the person who doesn’t care about investing into an amp which has to stay on the desk and plugged into the mains, the Rx is a great option. It also introduces great new technology which has proven benefits to all headphone users. While discerning IEM users may complain of low-level hiss and a power thump which at this price is somewhat perplexing, both of my thumbs are pointed skyward and my proverbial hat is tipped toward ALO and GR9.


Amp Summary
Title: ALO Rx Headphone Amplifier Developer: ALO Audio and GR9 Technologies
Reviewed Ver: Black!
Price: $345
  • Great looks
  • Solid construction
  • Effortless, multi-textured sound from IEMs to full size headphones
  • Excellent sound stage
  • Perfect stepped attenuator
  • Low-level hiss with sensitive earphones
  • Audible thump when power engages

Headphone amps and DACs help your headphones get the most out of their transducers. Take a look through our headphone section for suggestions of good upgrade/sidegrade options, and our headphone amplifier section for suggestions on how to wring out the best performance from your beloved phones.

Review-HPA-Rx-Cryo Review-HPA-Rx-DJ1Pro Review-HPA-Rx-Front-01 Review-HPA-Rx-Front-page Review-HPA-Rx-Glamour-01 Review-HPA-Rx-Glamour-02 Review-HPA-Rx-Rear-01 Review-HPA-Rx-TC Review-HPA-Rx-Box Review-HPA-Rx-amped-DJ1Pro-CT Review-HPA-Rx-amped-DJ13Pro-FR Review-HPA-Rx-amped-FX500-CT Review-HPA-Rx-amped-FX500-FR Review-HPA-Rx-amped-JH13Pro-CT Review-HPA-Rx-amped-JH13Pro-FRRead more]]> 10