So I managed to get the motherboard of my HTPC to transmit digital audio signal (tosslink) to my 990 (see earlier post) after updating drivers and what not.

As the problems on the PC side are solved my 990 is giving me grief. It's nothing big but I configured the audio input of the HTPC such that it is supposed to output 5-CHANNEL STEREO. However, when I turn the 990 OFF and then ON again the settings automatically revert to the default STEREO output. I am using the same cable and input (OPT1 IN) as for the CD player that was replaced by the HTPC. When the CD player was connected this never happened.

Any guesses?