Why no sound?

[Chuck Robey]

I haven't used my audio here for aboout a year now, but seeing as the connection
setup I'm using used to work fine with FreeBSD, I think I can assume that I
haven't any hardware misconnection problems, and my speaker system (which has
spdif input) allows me to select an internal noise generator for speaker testing
(balancing) so I know the speakers are OK also.

My problem is that I can get no sound out at all.

I've set my freebsd-current kernel with sound and snd-hda devices, and my
/dev/sndstat prints:

FreeBSD Audio Driver (newpcm: 32bit 2009061500/i386)
Installed devices:
pcm0: <HDA Analog Devices AD1988B PCM #0 Analog> at cad 0 nid 1 on hdac0
[MPSAFE] (1p:1v/1r:1v channels duplex default)
pcm1: <HDA Analog Devices AD1988B PCM #1 Analog> at cad 0 nid 1 on hdac0
[MPSAFE] (1p:1v/0r:0v channels simplex)
pcm2: <HDA Analog Devices AD1988B PCM #2 Digital> at cad 0 nid 1 on hdac0
[MPSAFE] (1p:1v/0r:0v channels simplex)

It's a Asus Striker Extreme motherboard, which has an internal ADI1988B chip,
which seems to be recognized fine by dmesg.  I'm certain I'm using a good test
mp3, and my connection is via spdif.  Mixer says all my outputs are on.  I can
play DVDs via vlc, but still no sound.  I can find no documentation whatsoever
in FreeBSD man pages as to what devices ought to be active here, but can anyone
give me a  hint as to what else I might try?