I am in Singapore doing an event, and as usual brought my Dave. But I forgot my USB cable, and Karl from AV one kindly lent me a $200 audiophile USB cable, as I wanted to listen to some mains cables with Dave using AQ Nighthawks. Anyhow, on the way back to the hotel, I passed a computer stores, and saw a $2 USB 2.0 cable, and bought it, so I would never be Dave less due to forgetting my USB cable.
Thought it would be interesting to listen to the two cables on Dave using headphones, as this is the simplest system - I don't have to worry about RF upsetting the power amps etc.
So listened to it, and immediately much preferred the $2 cable - much smoother, better instrument separation and focus, much more listenable. Initially I thought the audiophile cable was better - the bass was tighter - but this was just the brighter sound quality. Going back and forwards was inconsistent, so I formally shut down JRiver and ejected Dave from my Windows lap-top when going back and forth. Still preferred the $2, even though it was not supposed to make a difference to the sound.
Then I realised I had made a school boy error - the headphone cable was touching the USB cable. So I properly dressed the cables, kept the headphone cable separate, made sure the USB cables were in the same place every time.
Then - no difference whatsoever. The headphone cable was picking up RF noise from the larger audiophile USB cable, and that accounted for the difference in sound. So yes Dave is insensitive to the USB cable, as long as it is bit perfect data, and the RF characteristics do not affect any other part of the system.
I have noticed some posters talking about AES EBU input - this is not the best input IMHO. It will inject RF noise into Dave from the source, and this will make it sound brighter, due to more noise floor modulation. It is very easy to hear this as an improvement (like I initially thought the audiophile USB had a tighter bass) but this is just how RF noise can artificially spice up the sound. Instrument separation and focus will suffer - in the case of digital inputs, the smoother and darker sound (which can easily sound initially less impressive) is the best sound.
So far all of my tests have revealed that the source makes no difference to the sound, but this could be very system dependent. Dave for sure is intolerant, but your power amps or headphones may not be so. Also, when I did my tests, I left different computers on - powering down sources may make a difference, again results will be system dependent. I will be trying more things too.
My quick test with mains cables was interesting - but I need to do some more listening with different options.
Rob
