I think my sound not working is a hal/nohal issue. I just opened a 3.5.13-sru install with the in the exact same virtualbox environment and sound works beautifully. The only difference is that install loads hal and R14 doesn't. Have there been other sound problem with the nohal builds? I've attached my perirpherals-hardware-sound setup for review. It is the exact same between 3.5.13-sru and R14.
Start at the beginning. Find a wave file and test that the aplay command produces output. If not then run alsamixer.
Darrell