A few months ago we reviewed JustAudio’s AHA-120 amplifier and we found it was a great amp. Now it’s time to review its little brother, the µHA-120.

Unlike the AHA-120 (A class), the µHa-120 is the (more) portable amp of the two and it is a so called AB class amplifier. The version we received was a revision B, fitted with the optional “white velvet” pot upgrade. This more “basic” version of the AHA-120 doesn’t have the impedance selector on the front but uses jumpers to change the maximum gain setting. Ours was set at 6dB/12dB by Justin himself. Changing the jumpers is actually quite easy with the toolkit provided: with the hex key and battery tool it doesn’t even take 5 minutes to change the jumpers.

Both versions have a selectable power source (APSS). The specs for the µha and the AHA-120 are the same:

As you can see the maximum power is 56mW when using the USB power supply (32mW when battery powered). This is quite a noticeable boost when using a 300Ω headphone but even without the USB power the amplifier is still powerful enough.

Overall Sound Impressions

Right out of the box it sounded rather disappointing but that actually changed fast after a few hours and it has only gotten better. Soundstage of the µha-120 is definitely good, I’ve been enjoying it since the beginning, and as I already mentioned in the B&W C5 review, I have been using it nonstop. This little gem is neutral, it does not color the sound in any way. It’s very detailed in all layers, delivers great deep bass (it sure does have depth) and to my ears smooth nice mids and detailed highs. If I have to say anything it would have to be that it does emphasizes the bass, but I like it that way. I really can’t say anything wrong about the µHA-120, it has great resolution and it doesn’t sound airy or forced in any way. It sounds just right!

Justin insisted not to only consider this amp as a portable one and he suggested to hook it up to a stand-alone dac, and was he right… Its performance is way above what you would expect from a unit of this size, once again showing of its neutrality and driving everything from an Audio-Technica M50 to a Hifiman HE-500. Of course there is a difference between a full sized desk amp and the µha for what “body” is concerned but it does the job more than just ok.

I’ve been using this amp with my iPod, my laptop and at home and not one single combination has disappointed me in any way.  For all music styles I listened to, it was very realistic in portraying the instruments and it actually does great for all musical styles.

Comparison to the AHA-120

The A-class AHA-120, has a slightly different sound signature. The sound is much clearer and the soundstage is a lot bigger and more balanced. In lows, highs and mids everything has far more resolution and overall it is much easier and relaxing to listen to. Unlike the more portable µha-120 the focus isn’t on the bass section, there’s not really one point of focus. You get a less powerful bass as with the µha but it is far more detailed, the difference is very noticeable to say the least.

Both amplifiers have more than enough power you need and the advantage of the AHA-120 is that the impedance selector on the front allows you to slightly modify the AHA-120 according to you preference and headphone used but the differences are very subtle. The main goal of course isn’t to change the sound signature but to optimize the power supply so you get the best result for your headphone while not wasting power. (We explained this in detail before).

Since we last reviewed the AHA-120 in detail, JustAudio has modified its casing and now it has the same excellent build quality as the µha-120. The size of course is remarkably different but that’s the price you pay for an overall more qualitative sounding amplifier.

For those listening at home who prefer an even more balanced and detailed sound and a larger sound stage, I would recommend the AHA-120 which overall just has more quality. The fun award for me still goes to the more portable µha-120, it’s just great for when on the move.

Headphone Pairings

My beloved Sennheiser HD650(300Ω) was my favorite headphone at home with this amp and it was very enjoyable with good bass. The new Beyerdynamic T70 (250Ω – review coming up soon!) is easier to drive than the HD650 and the µha-120 does a great job, I’m convinced that the µha with the portable version of the T70, the T70P (32Ω) would be a killer combo! The little µha-120 performs exceptionally, even with big orthodynamics like the Hifiman HE-500 and the Audez’e LCD-2. They are the biggest challenge for this amp but at high gain it does get the job done more than just fine. Of course the volume has to go up a bit more then with the other headphones but it actually sounds very good, another positive surprise proving that this isn’t just a small portable amp for IEMs. That being said, with all the IEMs I tried, it did a great job.

Being honest I have to admit I do have some remarks as well. One I already mentioned in the C5 review and it’s about the plug. As the C5 IEMs can be used with an iPhone, the plug seems to distort the sound but by pulling it out for about 1mm it gets back to normal. The other remarks are about the volume dial. When using sensitive head/earphones, you can hear the music playing very very softly at zero volume and at very low listening levels there’s some channel imbalance, but all of this is minimal, it didn’t bother me at all. The other issue with the volume pot is the strong increase in volume between 9 and 10 o’clock which is more audible. Besides all these (for me) smaller issues the volume pot is very precise and very smooth to turn.

Design and Built

The look of the µha-120 is fairly basic, the front panel has the 3.5mm in/out, the LED and the volume dial while the back is the same as the AHA-120 with the charging and battery/usb option switches and the usb connection. It might not be as flashy as some other amps on the market but the build quality is very good and it feels great in hand, very robust. Height is 23mm, width is 52mm and length is 85mm which makes it about the same size as a pack of cigarettes, which means it fits in your pockets. Compared to something like the Fiio E11 it is twice as big, but it is also twice as good, at least. But seriously it really do is smaller as you think looking at the pictures. I like holding my portable rig in my left hand while on the move and found it very easy to adjust the volume setting when needed.

Charging the battery (only via usb) goes fast even at the normal setting and one charge lasts long! JustAudio claims up to 24 hours of operation time and I’ve been using it daily for about 5 hours a day and only after almost 1 week the LED indicator started blinking. For those always forgetting to reload their devices this is good news. Do be aware that when the LED finally does start blinking the µha will be shut down reasonably quick.

End Words

Justin and JustAudio have done it right again with this amp. It does everything you want it to, it sounds great, it is portable and it can handle about everything there is on the market. It’s pretty obvious that I love this amp and I can only recommend it. I won’t ever again say it’s “just” the AHA-120’s little brother, that’s for sure. I’m really sad to send it back to Justin. As a matter of fact I think I’ll mail him to buy it from him. I think that sums it up best: The µha-120 is a keeper.

Thank you Justin for giving us the opportunity to review another of your products and for making such a great amp within the £200 price range! More info about the British JustAudio and where to buy the µha-120 can be found on their website.

Gear used for the review: Hifiman HE-500, Audez’e LCD-2, Sennheiser HD650, Beyerdynamic T70, Audio-Technica ATH-M50, Fischer Audio Eterna Rev.2, B&W C5, Audio GD NFB3, Ipod, ZYCABLE Hi-end II LOD, iPad, Dell Laptop.

 

Mike has also written a review on the AHA-120.