Haven't tested it, but the manual for my Ayre DAC suggests that, for best performance, it should be run on a USB bus that is not being shared with any other devices. I have seen Gordon Rankin arguing the same on AA and CA, but can't recall the technical specifics.
Things I do not know but KG surely does. Confession, I did not buy one, it just seemed like it belonged here for some reason.
I've had a few, out of normal vessels.