There have been problems with the SoundBlaster driver recently.  I've
made a very temporary fix; all SB cards will be regarded as SB version
1.0.  This should make them work, but only on the simplest of modes (8
bits, mono, low sampling rates).

There is a real fix coming, but to do it right you need two things
that cannot be done cleanly in the current kernel.

If you didn't have any problems you can just delete the line
        sc->sc_model = 0x100;
in src/sys/dev/isa/sbdsp.c

        -- Lennart