Building a dedicated PC for high end audio system.

Id like to put together a very quiet system for use as a source in my high end audio system. Quietness is the most important priority with this system. I found out pretty quickly that my main rig wasnt very good for use in my audio system, especially when listening to classical music, the fan noise was clearly audible during very quiet music passages. So im trying to descide on whic cpu would be best to use if your going for a quiet system, which can be passively cooled?? Im looking at the AMD BE-2350 right now and it seems to be perfect for what id like to do. What do you guys think, is thi a good choice, any others i should be considering?? One other thing to consider is that id like to have enough cpu power to do some DSP such as Upsampling and DRC as well as play back the ocasional movie, so please dont reccomend one of those passively cooled VIA 800mhz cpus!
Thanks