Hardware Reviews

Innuos PhoenixUSB


Despite Apple’s best efforts USB has become the de facto connection for everything from rechargeable torches to watches, computers and digital audio. It was never designed to send an audio signal but the fact that most laptops can send digital audio via this ubiquitous connection mean it has become the way that the majority stream their music. It is however far from perfect as anyone who has tried to get engaging sounds from their computer will attest. Even those of us who use dedicated audio servers struggle to make their USB outputs sound good and for my part I had given up and taken to using the ethernet output and channelling it into a network streamer prior to sending it to my DAC.

When Innuos developed their range topping Statement server they decided to see what could be done to improve this state of affairs and developed a reclocking circuit for the USB output. Now they have taken the technology developed for that part of Statement and made it available as a standalone unit, the PhoenixUSB is a reclocker, regenerator and power line cleaner for any USB connection between a source and a DAC. It is very simple, so much so that there isn’t even an indicator to tell you that it’s turned on, because all you need to do is connect the output of your USB source to its input and connect its output to a USB digital analogue converter.


But what does it do. It reclocks the incoming signal with a very high precision OCXO master clock, that is a crystal oscillator that is kept in a temperature controlled case and has a microscopic error rate of three parts per billion, which makes it considerably more accurate than the clock in all USB sources and the majority of DACs. But why do DACs benefit from an external clock when they have one onboard already? Because it makes their lives easier if the incoming signal is clocked at precisely the right frequency with minimal errors, it requires less processing power which leaves it more energy to deal with the conversion process. This was demonstrated rather dramatically by the Grimm MU1 reviewed earlier in the year, that is not a traditional reclocker but it does control that aspect of the conversion process.

The PhoenixUSB has to regenerate the signal in order to reclock it and has two high quality linear power supplies onboard to make sure that this is done as accurately as possible and with as little noise as possible. One for the 24Mhz clock and another for the outgoing 5V supply. Noise is the enemy of sound quality and the reason why digital audio struggles to live up to the ‘perfect sound forever’ hype that it was launched with nearly 40 years ago. Which is why the final function of this Innuos is to provide an extremely clean 5V supply to the DAC. The powerline between USB devices is a major conduit for noise to get from the source to the converter, by reducing this the PhoenixUSB reduces the amount of noise entering the DAC.

In many ways the PhoenixUSB is an alternative to a network streamer such as the Auralic Aries G1that usually sits between an Innuos Zenith SE server and the DAC in my system. It doesn’t require a dedicated control app however, like all USB sources the app tells the server or PC what to send to the DAC, it’s a data pusher (conversely a streamer ‘pulls’ the data from the server). At present Innuos have not finalised their own control app but you can use one called iPeng to play anything on the server as well as streaming services like Qobuz and Tidal alongside internet radio. But the nicest way to control pretty well any streaming system is with Roon which while not inexpensive does make life a lot easier than the alternatives, primarily by working every time you turn it on, even if you muck about with the hardware. And, crucially, Innuos servers have a built in Roon core so it’s even easier to run.


Contrasting the direct output of the Zenith SE with the same signal going through the PhoenixUSB is like chalk and cheese, the reclocker significantly enhances timing definition; drums and bass become more solid and coherent and the soundstage deepens at the same time. Essentially the sound goes from meh to woah, especially with a great classical recording (Maxim Emelyanychev, SCO, Schubert Symphony No. 9 in C major, Linn) where the extra detail resolved and the coherence with which it is presented add up to a perceived doubling of scale, dynamics and melodic charm. For me it’s the timing that counts the most however, I find it very hard to become involved in a piece of music if the timing is out and that is definitely the case with the USB output of the server alone. The other things that the PhoenixUSB does, specifically the reduction in noise, help the dynamics and imaging make for a more lifelike musical experience though and that is also inspiring. And that’s before you put on something with real meat in the low end, the bass is so solid and articulate that beats with a bit of texture are absolutely delicious. Digital bass has always been well extended but rarely this fast or well resolved.

The reduction in noise also takes away the tendency for digital to sound grainy or hard, the Zenith SE server is very good in this respect already but as Innuos proved with the Statement it can be bettered, and this mute box delivers a result that’s very close. I love the taut pace it brings to more complex rhythms where different instruments are playing at different tempos, it makes bands like the Grateful Dead gel like nobody’s business. It’s hard to keep still whilst listening to that band throw down the jam when it’s delivered so well. And the near total absence of any insidious noise means you can play as loud as you like and appreciate why that band’s live performances had such a strong reputation.


It’s worth mentioning that unlike a network streamer a reclocker like this is not bothered about format because there is no conversion process involved. You can play anything through it from DSD through DXD to MQA, whatever you have will get to the DAC which is not necessarily the case with streamers. I don’t use non PCM formats very often but have a few albums in DSD including Tom Waits’ Rain Dogs which has been enjoying a renaissance on the turntable of late. The digital version isn’t far behind with the PhoenixUSB and an iFi Pro iDSD DAC in its non oversampled ‘bit perfect+’ mode, you can hear all the nuances of singing and playing and the vaudeville dramatics are as clear as day. Tonally the result is down to the DAC but this reclocker takes away the grain that can make digital recordings sound bright or edgy and delivers a clean and relaxed sound by the standards of its ilk, nothing is forced and every track played displays its character down to the quietest detail.

The PhoenixUSB delivers the best sound I’ve heard with a USB connection to date (I fear I didn’t give that aspect of the Statement as much attention as it deserves). It had me listening late into the night on numerous occasions, contrasting performances of Arvo Pärt’s Fratres for instance, Tasmin Little sounding sweeter and more melodic than Viktoria Mullova’s intense and dark approach but both of these violinists revealed the depth of feeling behind the piece. I didn’t get the chance to try the PhoenixUSB with a PC because my laptop died but I would expect it to do an awful lot for that type of source. I did try it with a Melco N1A server and got a similar upgrade to that with the Zenith SE albeit with the more mellow character of the Melco remaining. This device doesn’t change the sound of the source its used with, it cleans it up and gets its bits in a line so that it sounds a heck of a lot better. This is the most expensive reclocker I have encountered, but in terms of what it does for digital sound quality it is a very impressive upgrade, so the asking price seems entirely fair.


Type: USB reclocker, regenerator and power supply
Clock: 24Mhz, OCXO
Format: any
Power supplies: 2 independent linear supplies
Accessories: USB cable
Size H x W x D: 85 x 215 x 335mm
Weight: 6kg
Warranty: 2 years

Price when tested:
Manufacturer Details:
T +44(0) 2475 200 210



Jason Kennedy

Notify of
Newest Most Voted
Inline Feedbacks
View all comments