Hey there, I have a Media PC set up, with optical audio out from a SIIG SoundWave 5.1 PCI-LP audio card to my Denon AVR 1708 A/V Receiver. The signal is outputting to all of the speakers, but its just a stereo signal that's going to all the speakers. The audio configuration utility in Windows (I'm running Windows 7 Beta) thinks that its outputting to a 5.1 channel device. There are buttons you can press for each of the speakers, and the front left and front right work just fine. But when you press the center, rears or subwoofer, nothing happens. I am not sure if this is an issue with the receiver itself, or if its the computer. Any input would be greatly appreciated! Thanks!