What I really want isn't so much a port of ALSA to NetBSD, but an API
   layer on top of NetBSD's.


exactly; we need something akin to the compat_oss / -lossaudio that
we have to support OSS applications (in both compiled apps and linux
binaries.)


it would be vaguely cool to use alsa drivers but that's a LOT more work
than simply providing a compatible api/abi.


.mrg.