Hello,
everything seems to be installed correctly, fireface installed with latest drivers and
device manager says that the device is working properly.
However, when I open media player and try to play any mp3,
I get the following message (in German):
Windows Media Player kann die Datei  wegen eines Problems mit dem Audiogerät nicht wiedergeben.
Möglicherweise ist im Computer kein Audiogerät installiert, das Audiogerät wird gerade von einem anderen Programm verwendet, oder es funktioniert nicht.

which translates to:
Windows Media player can't play the file due to a problem with the audio device. Possibly there is no audio device installed, the audio device is being used by a different
program, or it does not work.

I got another installation of the same operating system on my machine (dual boot) - where Fireface works flawlessly.

Any ideas?
Thanks
Michael