sound cards are a hit-and-miss. I had a friend with a DA that used a PCI Soundblaster AWE32 PCI card in his, after he pulled it out of a PC that died, and it worked fine under OS X (OS X actually saw and used it w/o drivers). sadly, OS 9 doesn't see it.

But it works pretty good. All he needed it for was so he has RCA non-GAIN boosted ports (non-preamped) so he could convert his RCA Record player system into MP3s (RCA-style ports record player.)