oldcpu:

Thanks for the reply! I will try out what you said today or tomorrow and let you know how it goes. I was unaware of the speaker-test program so to test sound I was just trying to cat a raw sound file directly to the device:
cat endofworld > /dev/dsp. All I hear is a quick crackle. Any volume controls/mixers I try to bring up complain about there not being a sound device.

At the moment (in the absence of any better ideas) I am in the process of compiling the stock 10.2 kernel+modules to see if I can get 10.3 to run on top of the 10.2 kernel and see if it makes a difference.

Your ideas sound a little saner than my 10.2 kernel idea, but since I'm halfway through the compile I'm going to go through with it....