Has this been solved? You should update your system as there is a later alsa driver.
Code:
sudo aptitude update && sudo aptitude upgrade
Reboot and open alsamixer. You have a mixer control labelled "line" that is muted and at zero volume.
Play around with that.
Code:
 alsamixer
Press <F6> to select the correct soundcard.
Press <F3> to show playback levels. <F4> selects capture levels [or use <Tab>]
Use the left/right arrow keys to select and up/down arrow keys to change levels. <M> to mute/unmute.