Comment 2 for bug 1000098

it seems to be fixed!

The last values for the modprobe.d options I tried did the trick, but only after shutdown (simply rebooting do not work, i don't know why).
I followed the instruction of the last post of this thread: http://www.linux-archive.org/gentoo-user/566518-ff-chromium-trapped-deafness-how-configure-alsa-correctly.html (linked by this other one: http://www.linuxquestions.org/questions/slackware-14/slackware-13-37-audio-setup-seems-fine-no-sound-922521/), and I set the last line of alsa-base.conf as follows:

options snd-intel-hda model=auto,auto enable_msi=1,0 index=0,1 id=Intel,NVidia

Now everything is working fine.. (I hope).