there are 3 different ways a usb receiver may get its audio data from the pc: synchron, adaptiv and asynchron
here is a good writeup by Christiaan Puunter:
http://www.hifi-advice.com/USB-synchronous-asynchronous-info.html
short:
synchron (not used any more, clock-timing based on the usb timing)
adaptiv (normal mode today, clock timing more or less based on computer clock by recalculation of timing of incoming data)
asynchron (clock timing totaly based on clock chip in the usb receiver, receiver stores usb data and makes reclocking with own clock chip)
... so synchron and adaptiv mode tend to have jitter problems (working with computer clocks is not very "stable in timing"), asynchron mode should not (or the clock chip is bad)
Sandro
Edited by boushh - 1/16/13 at 6:26am