OK...I've been going nuts. I have a Shuttle XPC SN95G machine hooked up to my plasma. It's not really a dedicated HTPC, but I've tried to make sure it has everything it needs. It absolutely flys in Doom III at full rez. I'm only getting two channel audio over the optical, or coax digital outputs whether in Doom III or playing a DVD...ripped or otherwise. I'm using no analog connections but no matter what I do my receiver doesn't recognize that there is any multi-channel encoding. The motherboard specs say... On Board 5.1 Channel AC97 Audio Compliant with AC'97 2.2 specifications. 5.1 channel slot selectable DAC Output for multi-channel applications. I'm using the Nvidia nForce driver 6.14.457.0. (4.57 looks to be the newest driver) The NV mixer utility info shows that the codec capibilities are "Single AC'97, 6 channels" When I run the speaker setup wizard in NV Mixer, it identifies that there is digital signal, but at the end it says it's only using two channels. If I was getting no audio over the digital connections I'd almost feel better, but I do get sound...just not Dolby Digital, DTS, or multi channel period. This is the built in sound card but I'm not asking it to do any decoding...just pass the signal to my Denon 3805 and let it handle it. Any ideas?