We have the same soundcard
I know I won't be able to play SACDs, but in non-scientific tests (just listening to one format and the other), I can't tell the difference. I have a Denon receiver of the type you mention and I do almost the same thing you do now, but I can't set up in another room just yet.
I'm saving up a few grand for a good audio system and want a source that's equally good. Keeping it in the same room would be a priority because of logistics, which is why I want to go silent. I also like the idea of having it as a system component that is used exclusively for music, than as a PC that just happens to be hooked up to my system (what I have now).
To further answer the earlier question about what a silent PC is, it's defined as having a noise level below the ambient noise in a room - usually around 25-30 dB or something like that.
Thanks for the input.
-Matt