Adam,
Now that I have tried all of the "high end" USB cards, including SOTM, Pang V1 and the new JCAT I think the new JCAT is the winner. I have two Caps Zuma one that is now dedicated to the JCAT and am waiting for my dual rail LPS from Core Audio. The Pang card is a significant improvement over the SOTM but the JCAT is a whole new level. WARNING, let it break it for at least a week before drawing any conclusions. Right out of the box, it is very shrill.
Marcin promissed to send me one this week.