Audio out via HDMI... how?

[Ronald F. Guilmette]

I have a laptop which has an HDMI output port.

I can get video out of that (with xbmc) just fine.  Audio, not so much.
Like not at all, as far as I can tell.

So anyway, here is what I get when I do "cat /dev/sndstat":

pcm0: <HDA Realtek ALC888 PCM #0 Analog> (play/rec) default
pcm1: <HDA Realtek ALC888 PCM #1 Analog> (rec)
pcm2: <HDA Intel Cantiga HDMI PCM #0 HDMI> (play)

I have the HDMI output wired into my everything-capable Sony 5.1 channel
receiver, which then in turn is wired into my 4 (count 'em four) speakers.

OK, so now, could somebody please just tell me how I can do a test
that will determine why I ain't gettin' no audio?

The receiver is capable of decoding 5.1 DTS-HD, Dolby TrueHD, and eveything
else too.  It is working just fine.. not a thing wrong with it.  It works
great with my Blu-Ray player and does the digital->analog decoding for
anything and everything I throw at it.

Again, I just want to know how to _test_ doing some output to that from
my laptop, via HDMI.  I tried these things, but not a sound was heard:

   cat /dev/random > /dev/dsp

   cat /dev/random > /dev/dsp2

The FreeBSD handbook page that deal with setiing up audio cards doesn't
provide a whole lot of guidance for how to test and/or fix digital audio
output, whether it is coming out via HDMI (as in my case) or via any other
kind of physical transport (e.g. coax or S/PDIF).

Somwebody please pass me a clue.  I'd really like to get this working.
Thanks.

P.S.  If I have to downmix to 2ch in xbmc before the audio even hits the
HDMI cable, I could even live with that.  Bu right now, as far as I can
tell, I can't get _any_ audio flowing down that cable, period.