[jff]

The thing to keep in mind is that this was written for a SoundBlaster back in the early 90s. I remember being really impressed that Commander Keen 4 could use the SoundBlaster 16 in my 486 to make decent music at all.

As for notifications of device property changes, you would probably get them by reading from the various control and status files. Although I use Plan 9 at home and at work, I have never really done anything with audio, I'm afraid.