my friend and i are having problems with this sound card that we bought especially for the 360 so that i can have sound with my existing pc speakers. im using klipsche pro media 5.1 and a dynex 7.1 sound card with a model number DX-SC71. We can get pc audio working no problem but when we hook up audio via its optical input to the 360 we get no sound at all, we have the 360 set to dolby digital so i believe the 360 settings are correct. Anybody know what the problem could be? thx