help with multichannel sound, alsa 1.0.x

Hello, I have just spent a few hours trying to get surround sound
working with Ogle 0.9.2.  From the alsa test in configure script it's
clear that nobody is using this with Alsa 1.0.x...  I happen to have
Alsa 1.0.1, so I tweaked configure to allow ogle to compile with alsa
support.  The default oglerc now gives me fine two-speaker sound.

However, my motherboard (nforce/shuttle AN35N ultra) has outputs for
rear and center speakers, and I'd love to have them working.  So I
uncommented the "if you have a multichannel card" section, and tried
ogle again.  When the title screen comes up, I hear a loud, annoying
clicking sound instead of the normal audio.

Here are the logs:  http://www.deconfusion.org/tmp/ogle/ogle-debug.txt

I tried removing the AC3 section and I get a slightly different clicking
sound.  I'd like to figure out what I'm doing wrong, but the manual is
no help - it doesn't even mention that AC3 is a possible chtype, so
there is no way to figure out what the difference between AC3 and the
explicit channel listing is.  The FAQ and Google were no help here.

Can someone explain the difference between the different types of
channel settings, and what those are actually for?  Do they control how
the sound is read off of the DVD, how it is sent to the sound card, how
sound is processed internally by ogle, or how the sound card is
configured?  Shouldn't all four of these be independently controlled?

Someone mentioned that you might have to specify an explicit alsa device
name - how do I find the list of names and options?

Finally, if anyone has multichannel sound working on an nforce board,
please let me know (and send your oglerc).

Thanks!
-Paul