FreeBSD supports various sound cards (for more details, see FreeBSD Release Information and the snd(4) manual page). There is also limited support for MPU-401 and compatible MIDI cards. Cards conforming to the Microsoft® Sound System specification are also supported.
Note: This is only for sound! This driver does not support CD-ROMs, SCSI or joysticks on these cards, except for the SoundBlaster®. The SoundBlaster SCSI interface and some non-SCSI CD-ROMs are supported, but you cannot boot off this device.
4.6.2. Workarounds for no sound from my pcm(4) sound card?
Some sound cards set their output volume to 0 at every boot. Run the following command every time the machine boots:
# mixer pcm 100 vol 100 cd 100