I've been fighting with this for quite some time myself. The only sound I got was through the headphones but in no way I could get the speakers to work. And then I got adventurous and installed the Liquorix kernel and whoopy, it just started working and I haven't encountered anything that's not working. Not only am I using a 'rolling Debian release' but on top I'm working with the 2.6.37 kernel!
If you want to try (take backup of your important stuff, just in case!!), here's what I did.
sudo nano /etc/apt/sources.list
# add repository:
deb http://liquorix.net/debian sid main future
# Save and exit by 'ctrl+x' 'y' enter
# Save the keyring
apt-get install '^liquorix-([^-]+-)?keyring.?'
apt-get install linux-headers-2.6.37-0.dmz.4-liquorix-amd64 linux-image-2.6.37-0.dmz.4-liquorix-amd64
After installation of a new kernel, of course you'll have to add any kernel modules you've added manually before.