I have FreeBSD on the machine in my office. FreeBSD is a nice system and does some things really well, particularly things related to data storage and networking. Unfortunately, my experience with audio on FreeBSD has not been very good. Several times I have noticed slight distortion of the signal during playback and during recording, on all sorts of hardware. This is with kernels 6.1, 6,2, and 7.0-current (May 28, 2007). And there is never any kind of error message. Even my good external soundcard, the Edirol UA-25. has glitches when operating in FreeBSD. My ear is sensitive, not the most sensitive. The exact same hardware sounds great under Linux. So I now boot into Linux when I'm doing audio stuff.
By the way, the Edirol UA-25 is a great piece of hardware. It is simple and does its job very well. I salute the people who made it.