Comment 26 for bug 420578

The patch mentioned in comment 25 has been included in the newly released 2.6.34-rc3 linux kernel. From the changelog:

commit 025f206c9e0f96cc41567b01c07fb852d8900da1
Author: Daniel T Chen
Date: Sun Mar 21 18:34:43 2010 -0400

    ALSA: hda: Fix 0 dB offset for HP laptops using CX20551 (Waikiki)

    BugLink: https://launchpad.net/bugs/420578

    The OR has verified that his hardware distorts because of the 0 dB
    offset not corresponding to the highest PCM level. Fix this by capping
    said PCM level to 0 dB similarly to what we do for CX20549 (Venice).

    Reported-by: Mike Pontillo
    Tested-by: Mike Pontillo
    Cc: <stable at kernel(dot)org>
    Signed-off-by: Daniel T Chen
    Signed-off-by: Takashi Iwai

There is a Karmic PPA of this kernel RC available at http://kernel.ubuntu.com/~kernel-ppa/mainline/