I am not sure what audio server FreeBSD uses but OpenBSD uses sndiod
http://www.openbsd.org/cgi-bin/man.c...1?query=sndiod
which is an intermediate layer between audio or MIDI programs and the hardware. OpenBSD just like all BSDs, Solaris, and Linux in the distance past use OSS. If you are musician you might want to look at OpenBSD which is commonly used as a mixer platform for large rock concerts. OpenBSD plays multiple sound streams out of box of course just like OS X or Windows.