hda-emu codecs/alc662-intel-d945gclf2
But it's irrelevant from whether you enable independent HP mode or not. It's just the policy of badness evaluation. It's possible to have a different result by adjusting the badness parameters.
IOW, the patch like below will make surrounds back for the device, for the cost of losing individual headphone volume control.
It seems that it would make more sense for having surrounds for such desktop setups, and the patch doesn't appear to affect too severely. Only ALC662/663 and one CMI9880 configs have been changed by this, and all look reasonable. So I'm going to apply it.
BTW, I should mention beforehand that the previous patch won't suffice for the device like ThinkCenter A58 where the headphone can't be shared with the primary DAC. For allowing the surrounds on such machines, we need to implement more complex workaround (i.e. make surrounds exclusive, and turn off others while using surrounds).
http://www.intel.com/content/www/us/en/motherboards/desktop-motherboards/des...
Realtek ALC662* codec for 2+2ch (multi-streaming) Intel® High Definition Audio (Intel® HD Audio): Front panel microphone/headphone header S/PDIF digital audio header Internal mono speaker header
https://launchpadlibrarian.net/92117241/Card0.Codecs.codec.0.txt
The result of hda-emu seem OK for ThinkCenter M55 (AD1988) which have volume controls for the internal speaker
https://bugzilla.redhat.com/attachment.cgi?id=335481
But have same problem with those 6-channel HDA codec
M57/M57P(AD1882)
https://launchpadlibrarian.net/63326460/Card0.Codecs.codec.2.txt