USB cable..what do you have.

Here is a white-paper on sources of jitter:

http://www.positive-feedback.com/Issue43/jitter.htm

Not all asyc USB interfaces are immune to jitter BTW.

Steve N.
Empirical Audio

Thank you, Steve.

Could you, please, elaborate a bit on "Not all asyc USB interfaces are immune to jitter BTW"? I'd like to understand.
I might be wrong, but if the connection is asynchronous, that means that there is no timing sent through it, thus no interface jitter exists.
Jitter from the ADC itself will be there, in the data itself, that's clear, same for the jitter of the DAC's own clock, but that's not what I was referring to.
I meant that transport and interconnect jitter will be out of the picture in the async USB case.
Where am I wrong?

I'm in for a Locus Design Cynosure. I've worked my way through their line and have noticed leaps and bounds improvements all the way up. I'm thrilled with the product, and with Lee's generous upgrade policy.

The Locus Axis is awesome!

"transport and interconnect jitter will be out of the picture in the async USB case. Where am I wrong?"

You are not wrong. I have done several async designs, some even with FIFO reclockers isolating the USB and the output. There are still cable effects. Doesn't make technical sense, but there you have it. Ask Gordon of Wavelength or Hansen of Ayre. Same thing. It happens and we dont know why. We can speculate on mechanisms, but noone has the answer yet to my knowledge.

The effect is undoubtedly lower than with Adaptive mode interfaces, but it is evidently still there to some extent in most systems.

I find in my system that the effect is so small that I dont bother with expensive USB cables anymore.

Steve N.
Empirical Audio