Comment 8 for bug 541802

I have the same problem with what looks like a very similar chip, I would guess it's probably related:

Intel Corporation N10/ICH 7 Family High Definition Audio Controller (rev 02)
Conexant CX20551 (Waikiki)

Basically I get distortion on all volumes because PCM is always set to around 100% by ALSA.  I had this problem in Karmic as well.

I fixed it with a config tweak that I read on a Wiki somewhere, I can't find it at the moment otherwise I would share it here.