I couldn't get one of my CDs to play audio, either by enabling of digital audio, or by a standard cable. However, reading this thread did remind me to turn on DMA (33), and now it works fine with both the standard cable method, and with the digital audio method. Go figure.
As a bonus, I can now read audio from my CD-RW as well, because I turned on digital audio for it. (Both my CD-ROM and DVD-ROM have digital out hooked up to my SB Live! so I turn off the digital audio option in Windows 2000 to save CPU cycles. The CD-RW has no digital output.)
Now, for my Promise Ultra66 card, DMA66 is enabled by default right? My hard drives are on that card.