I used to use with the atennuator because my system used to be bright. I tended to prefer a more laid back sound as it added a sense of depth to the soundstage, otherwise things can sound a little forward with my old system. Using a short USB seemed to have a big influence on the sound, much tighter timing and more focus to the sound, but also possible brighter. To make things even more complicated there is the Young drivers which also sound different... In the end I think I was using 7cm USB cable, 20dB atennuator, and original HiFace drivers, but there is no right answer really, and I'm not sure what I would use with my current system (my DAC, amp etc were not so transparent before, so I'm not sure what setup I would use with the JKSPDIF mk3)