| posts: 90 | Location: Mexico
I have that receiver, and from a whole weekend trying to get surround sound from my computer and from my Bluray to work I found a few things:
The only input that support surround is the SPDIF (coaxial and optical).
The HDMI it's only to switch from your dvd, bluray, etc to the TV. The receiver won't take the audio from the HDMI input.
If your sound card supports encoding the sound in Dolby Digital Live or DTS Interactive, you can send 5.1 audio through the digital out to the receiver, if you can choose, I think that DTS interactive sounds a little better.
I know that some onboard soundcards support this, and some discrete ones too.
The Xonar DS supports DTS interactive, and I think many other Xonars too, but I don't know which ones.