Originally Posted by emcdade
Yes, the sender sends a squarewave electrical signal through the cable the the receiver. The squarewave is susceptible to noise and interference the same as any other electrical signal. Any cable that preserves the correct squarewave is ideal, and any poor quality cable that allows degradation to the squarewave is bad.
Whoever wants to hook up their DAC with the cheapest printer cable you can find, be my guest. I'll pay a little more for my cable and the world will keep on turning.
You're confusing digital and analogue. As long as the voltage of the top of the squarewave is above a certain threshold then it is registered as a 1. Below a certain threshold and its a 0.
It then stores that 1 (or 0) in the buffer. It loses all sense of the noise. It doesn't store a sort of 1. It doesn't store .995 or .005. It's a 1 or 0.
A little bit later, the DAC, at the timing of it's choosing, looks at the buffer and decides what to do with that 1 or 0.
The entire point of the USB specification is to certify that any CERTIFIED usb cable and CERTIFIED usb connectors will work. I don't know about you but the printer cable I just looked at is certified, so I'd 100% trust it.
The funny thing is there is a very valid possibility where USB audio could have major noise and drop outs. You haven't mentioned anything about the fact that usb audio uses the isochronous functionality of USB transfer, meaning if there is a checksum (crc) error then the data isn't resent. Again though, either the cable works or doesn't. It isn't going to magically make voltage disappear one second and re-appear the next. This may be the "noise" you refer to on some systems But then I challenge you to prove that both the sender and receiver were in compliance and using a certified USB cable. But changing for a different certified cable reduced the number of checksum errors.
Edit: I see you added the cost of your cable after I posted so I'll say this. $50 is crazy. Absolutely. Go spend $11 on a regular certified cable and send the remaining $39 on charity. Multiply that by the number of crazies buying crap like overpriced usb cables and it's downright depressing.