>   What are my options? Everything from the FreeBSD ports audio
> collection wants sys/soundcard.h.
Take any of the mixers in pkgsrc/audio.  They have all been
ported to NetBSD.

Generally, programs that want sys/soundcard.h are pretty easy
to port to NetBSD.  You need to include soundcard.h instead,
link with -lossaudio, and probably change /dev/dsp to /devaudio.

        -- Lennart