ALO Audio’s The International headphone amp/USB DAC in review
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
Output Power – Unbalanced:
130 mW into 32 Ohms
160 mW into 300 Ohms
200 mW into 50 Ohms
83 mW into 600 Ohms
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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