USB vs coax


USB vs coax
Thursday, April 14, 2016

Ever since I started using the Melco N1A server as a source for digital files there has been the option of connecting the USB output directly to a DAC or using the network output to drive a streamer and plugging a coaxial digital output into the same DAC. It’s not a totally flat playing field because I have only just got a coax and USB cable from the same manufacturer and range, most of these observations were made with my coax cables from Chord Co and USBs by CAD and Vertere. And of course in one instance there is an Ethernet cable and a lump of electronics pulling data off the Melco’s drive.

Those extra elements in the signal path should make things worse, however, coax consistently sounds better than USB. By better I mean more engaging, interesting, dynamic and better timed. This has been the case with a range of DACs including COS D1, Bryston BDA3, Lampizator Lite 7 and Marantz SA14S1 SE as well as servers; the Melco and CAD’s pricey but excellent CAT. USB often sounds more detailed and holographic so I can see why some might prefer it, with the Bryston BDA3 DAC and Bowers & Wilkins 803 D3 speakers the sense of being there is palpable when you play a great recording. Low level resolution is stunning and this makes for tremendous realism. It does not however make for as much musical thrill power as when you stick a Naim NAC 272N network streamer in between server and DAC. I’m only using the streamer from the Naim, not its DAC or preamplifier, and I’ve done this with other streamers (Moon Mind, Cyrus X Stream, Primare PRE60) with the same effect.

The track ‘Bermuda Blues’ by the Henry Threadgill Sextett (You Know The Number, Novus) makes a very good case for the streamed approach, it’s an older recording of some intense but swinging jazz played on brass, drums and percussion by six individuals. On USB it doesn’t sound that good and makes little musical impression, you don’t really listen to it. Via the network and coaxial digital it turns into more fun than you’ve had with your clothes on, it swings like a proverbial mother and has more energy, joy and dynamism than you could have imagined with the previous connection.

It’s the old detail versus timing debate that has split enthusiasts for far too long but if you have been wondering why your streamed tunes don’t sound as good as your vinyl this is one area to investigate. With streamers like the Moon Mind and the even less expensive Auralic Aries Mini being available for sensible amounts it is possible to try this approach without too much fiscal commitment. I mentioned this to Nigel Finn at Chord Co who was using the Moon streamer for his Bristol show demonstrations, he agrees that it’s “the more musically coherent option” and has a theory as to why. This is that most USB cables for digital audio are exactly like their computer counterparts but made with better materials, and that the driving force behind computer USB is cheapness. He reckons that there are other ways to skin this particular cat, eg making a cable that works best for audio but does not necessarily comply with the USB standard, which is also the approach Chord Co takes with Ethernet network cabling.

Talking to Nigel about this subject inspired him to lend me a piece of the new Sarum Super ARAY USB (above left) which made an interesting contrast with the RCA terminated ‘Digital’ version of the same – they don’t call it a coax because it’s not coaxial. Here the difference was quite big but not in quite such a clearcut way, that is the USB revealed quite a lot more depth and character but sounded drier than the Digital which seemed quite a bit more juicy and fat and had a more convincing presentation. The SSA USB seemed to time well though, nearly as well as the Ethernet/streamer/coax combination.

There are still too many variables to make blanket statements about the two routes, the only way to do that would be to get a streamer with USB and coax outputs but I’ve not tried one of those yet. In the meantime these findings make a good case for a dedicated streamer over a computer source.

Jason Kennedy