I am using a Samsung Chronos 7 laptop with the following sound setup:
$ head -n 1 /proc/asound/card0/codec* ==> /proc/asound/card0/codec#0 <== Codec: Realtek ALC269VC ==> /proc/asound/card0/codec#3 <== Codec: Intel CougarPoint HDMI
With the stock ALSA that comes with Ubuntu 12.04, I do not get any sound out of the headphones when I plug them into the headphone jack. After plugging the headphones in, I have to manually use Alsamixer to increase the volume, so that the headphones become usable. I have been told that this issue is due to my sound chip not being supported in the ALSA version that ships with Precise. A similar question at AskUbuntu and the Ubuntu Community Documentation point me to the ALSA DKMS installation.
After installing the dkms module of yesterday's ALSA snapshot and rebooting, the headphone issue is indeed solved. I can now plug my headphones into the jack and instantly have sound on them. However, now I have tons of static noises and crackling when playing sound in VLC player or Skype (Firefox HTML5 playback seems to be fine, unless a Skype sound interferes with it). Is there a fix for this? I tried adding the Alsa PPA and installing the latest ALSA package proper, but that didn't have any effect, only the Alsa DKMS package seems to solve the headphone issue.