Gosh, what a chock Glad I'm using an external amp, so I don't have to worry about that WASAPI issue
I switched back to Xonar ST in my Linuxbox, they do sound different but really at the same level of resolution, but ST is mabe more analogue and darker sounding and the Z is a little more analytical and with slightly more pronounced treble while not harsh. The ST has a wider soundstage, but the Z is not narrow. I'm still running stock OP on the ST but have 3 brand new 4562:s coming in the mail today, mabe they will push ST to best of both worlds ie a little less dark while overall the same. Both soundcards are very noise-free, I can have extremely high sound levels and it's still totally silent between songs.
I was inspired by the "192kHz Stereo Direct"-mode on the Z so i made some extreme settings in /etc/pulse/daemon.conf:
Which should match the "Stereo Direct"-mode in the type of signal fed to the DAC, but the above settings have the disadvantage of doing the resampling/oversampling on the cpu however no big problem on a reasonably fast Quad-core. If one has a cpu one should use it! I had to spec a large bufffer in the above file, for the sound not to stutter while doing other cpu-intensive tasks, and it doesn't. The resulting sound is like I described it above, very good, but so are the Z-sound