ALO the Pan Am Headphone amplifier/DAC in Review

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.

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

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