Hardware Reviews

Desktop USB amplifiers


It all started when someone said it was hard to find compact amplifiers that you could plug into the USB output of a computer and use with a pair of small speakers on the desktop. It turns out that this is a relatively rare breed and the selection we have gathered represents a fair proportion of what’s on the market. Presumably the desktop audio market is dominated by powered speaker systems and headphone amplifier/DACs, but there is clearly some benefit to be had from using decent amps, DACs and speakers with computer sources. Even if you are using iTunes or the Windows equivalent the quality of anything above base level MP3 warrants a decent system, and if you are playing lossless FLAC or ALAC (Apple Lossless) files then the difference between a basic system and one costing not a huge amount more is going to be quite dramatic.

We tested four alternatives from Denon, TEAC, ProJect Box Design and NuForce, all of them being small yet equipped with digital to analogue converters and enough power to drive the Triangle Elara, Dali Royal Menuet II and Q-Acoustics 2010i speakers used for this review. The source was a Macbook Air running Audirvana Plus software with Vertere Dfi USB cable and Supra Ply 3.4 speaker cable. Nothing too fancy in other words, we tried to keep things real given the price of equipment under scrutiny. If you want to get more out of your desktop listening experience, or for that matter need a compact amp with Bluetooth then there will be a model in this group for you.

Music used
Barenboim, Symphony No.7 in A, Op.92 Beethoven For All (24/96, Decca)
Red Hot Chili Peppers ‘Walkin’ on Down the Road’ from The Uplift Mofo Party Plan  (Manhattan)
Aaron Freeman ‘Covert Discretion’ from Freeman (Partisan)
Dave Holland and Pepe Habichuela ‘Hands’ from Hands (Universal)
GoGo Penguin ‘All Res’ from Man Made Object (Blue Note)


Denon PMA-50 £399

denon pma50
The largest amplifier in the group the PMA-50 is still pretty compact at 8cm high, it’s feature rich with Bluetooth aptX, DSD128 ad NFC touch pairing making it very mobile friendly. It came packed with a USB lead, Windows driver disc and a proper IEC mains inlet – many at this price have figure 8 power connections. That said the shrouded nature of the back panel makes connections fiddly if you are having to reach behind it. We liked the OLED display with its clean cut font and reasonable size of the remote, some are very small indeed but this has tactile buttons and will take slightly longer to lose!

Sound quality is best described as relaxed and easy to enjoy, it could have a bit more definition to the leading edges but there is plenty of power and bass weight available for the tracks that warrant it. Flamenco guitar is very nice, vivid and dynamic with decent definition of the double bass. The electric bass on ‘Walking on down the Road’ is good and round and the power of the recording is just as evident as the compression used to make it. Our Beethoven piece had decent scale and depth, sounding refined and effortless with good dynamic range and openness. All in all the Denon is a smooth operator and it’s large feature set means its ready for most anything you throw at it.

denon pma50 rear


NuForce DDA120 £350

nuforce dda120
Inarguably the coolest looking product in this group is NuForce’s ultra discreet DDA120. Some might say its pinhole display is a little too subtle but that’s clearly nonsense, just use the rather flimsy remote control and bathe in the minimalism. The DDA120 looks rather better than its specs read, USB is limited to 96kHz while coax will push this a little higher but not beyond 176.4kHz. All of which suggests a less than youthful DAC chip, but this is actually the sample rate of the amplifier itself, this a PWM digital amplifier that can work directly with a digital signal and only has to convert to analogue at its output. A point in the NuForce’s favour is that the price has dropped considerably in recent times, the DDA120 once retailed for £600, a fact that can be felt in the high build quality. The NuForce is slim at only 5.1cm high and offers 50 Watts per channel. It comes with a Bluetooth aptX dongle that connects to a USB A socket on the back.

Listening to the DDA120 you can hear its digital heart in a tight, clear and detailed presentation that brings out the layers in ‘Covert Discretion’ by revealing low level sounds that others miss. It’s not as expansive or rich a sound as you get with the Denon for instance and is noticeably happier at higher volume levels. The tight bass , power and pace it delivers make this an intriguing option but the limited feature set, inability to process 24/192 and basic remote hold it back in the context of the assembled competition.

nuforce dda120 rear


Pro-Ject Box Design MaiA £399

project maia
Box Design is the electronics wing of turntable company Pro-Ject, which makes a huge range of amplifiers, DACs, streamers and pretty much any type of audio electronics. The MaiA is one of the smallest amps in the range, so slim that it needs an external power supply so just has a small power inlet on the back. MaiA is more of an all round amplifier than the alternatives here with two analogue inputs and a phono stage, useful if you have a turntable. It has sub or second system output as well as a quarter inch headphone jack and runs a 24/192 DAC that is not DSD compatible. The front panel is minimalist with small input legends and buttons to scroll between them next to a motorised volume control that you can drive with the small, simple remote, another candidate for the crevices of your couch.

In the system MaiA seemed a little short on power with our speakers, dynamics were restrained and the balance was treble strong. It made us think that maybe the bigger MaiA DS would have been a better choice but that’s nearly twice the price. The standard MaiA has a pared down presentation that works with pacey material like GoGo Penguin’s piano driven grooves and it delivers plenty of detail and drive with the flamenco guitar of Pepe Habichuela. However the assembled alternatives do have more in the way of power and tonal richness which suggests that you need carefully chosen speakers to get the best out of this undoubtedly compact amplifier.

project maia rear slim


TEAC AI-301DA £399

teac a301da
TEAC has a long reputation for making attractive and well built compact separates, one that this amplifier maintains with its all aluminium construction and good detailing. The AI-301DA has a good feature set with DSD compatibility, two analogue inputs and the biggest remote handset in this group. The sockets and connections are all good quality and you get proper binding posts for the speaker cables alongside an IEC mains inlet, allowing power lead upgrades should the notion appeal.

In the system this TEAC proved to be the most entertaining amp in this group thanks to a degree of transparency to the source that meant you heard more of each piece of music. So Aaron Freeman was a bit mellower than usual but the doubling of vocals was easy to hear and the guitar strings sounded lovely and crisp. The Pepe Habichuela sounded excellent and reflected the quality of the recording well, the result being just that bit more sophisticated and revealing than its nearest rival the Denon. The Beethoven had good depth of image and lovely musical flow while there was real power on tap for the Chili Peppers despite the low specified 15 Watt output. This TEAC can do lively and engaging as easily as it can deliver a relaxed, effortless tune, this combined with the high build quality makes it our group winner.

teac a301da rear


This group proved that small can indeed be beautiful when it comes to amplification, all of these boxes fit comfortably under the screen of my 27inch iMac and the least powerful in spec terms (TEAC) proved to be the most enjoyable. It was a close fought battle however and all of the contenders deliver a result that makes budget powered speakers sound lame. You need to add speakers to these amps to get sound of course but these do not need to be huge or expensive, indeed the Q-Acoustics 2010i are neither (£90) but deliver an engaging, wide band sound that will make your music addictive. The option exists to add a subwoofer on most of these amps but as a rule they are better off left alone, you get more thump for sure but timing and ultimately musicality tend to suffer unless you spend more than these amps cost.

mini amps remotes



USB amplifiers


Jason Kennedy

Distributor Details:



Pro-Ject Box Design
T 01235 511166

T +49 (0) 8142-4208-141

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