Open
/etc/modprobe.d/alsa-base.conf
add the line:
options snd-hda-intel model=ref
Instead of 'ref';
http://lxr.linux.no/#linux+v3.2.19/Documentation/sound/alsa/HD-Audio-Models.txt
Is a list of models- instead of model=ref put in your model- or the most similar, eg, im running a hpdm4, I use model=hp-dv7-4000
I then use alsamixer from terminal to alter the volumes of the speakers, discovering as i do that bass is coming out the front speakers, and other channels through the subwoofer.
There is a method to swap these, but you will have to google it!(am in a hurry)
Paul