Fill out a bug report form please. There is a link tell you where to send the form. If you had read that thread as I asked you would have found the email address for the Xonar team, and that would have answered some of your questions. A single thread with bugs would be too much to sift through asking people for repeat info, which is why we keep it to single threads. That and the fact that the Xonar team set up an email address for bug reports...
The initial driver had some issues with Punk Buster. Not sure about S/PDIF as I don't use it myself. And nobody can offer advice because you have not told people which driver version you are running.
Yes I am employed by ASUS, although I only cover North America and I work in Technical Marketing.