I've read good things about the Revolution sound card. Although, personally, I think wanting to watch surround-sound movies on a computer is rediculous. Surely the couch in your living room is a better place for that. I've no need for seven speakers in my 10 x 10 foot office.
I also won't be buying a G5 Mac for years to come, so it's digital audio outputs won't come to my benefit for a long time.
Like a video card benefits overall performance by taking video tasks off the CPU's back, I would expect a sound card to do the same. All I'm looking for is some sound & performance improvements for when I listen to music while I work or when I play games. Surely a mid-level Soundblaster (or equivilent) is all I need.
To my surprise, the reports I read about the OS9 Soundblaster and some about the Revolution show decreased overall performance with the cards. To me, that's completely backwards to why one would want a sound card.
Roland's observation about the digital audio connections on the G5 probably answers my question, however. Apple doesn't have any plans to support sound cards - why would they engineer a digital audio connections into their new Macs otherwise?