The next thing I would try is turning up surround volume. It could be swapped with Master volume.
ac97_clock - AC'97 codec clock base (0 = auto-detect)
ac97_quirk - AC'97 workaround for strange hardware
See "AC97 Quirk Option" section below.
buggy_irq - Enable workaround for buggy interrupts on some
motherboards (default yes on nForce chips,
buggy_semaphore - Enable workaround for hardwares with buggy
semaphores (e.g. on some ASUS laptops)
spdif_aclink - Use S/PDIF over AC-link instead of direct connection
from the controller chip
(0 = off, 1 = on, -1 = default)
AC97 Quirk Option
The ac97_quirk option is used to enable/override the workaround for
specific devices on drivers for on-board AC'97 controllers like
snd-intel8x0. Some hardware have swapped output pins between Master
and Headphone, or Surround (thanks to confusion of AC'97
specifications from version to version :-)
The driver provides the auto-detection of known problematic devices,
but some might be unknown or wrongly detected. In such a case, pass
the proper value with this option.
The following strings are accepted:
- default Don't override the default setting
- none Disable the quirk
- hp_only Bind Master and Headphone controls as a single control
- swap_hp Swap headphone and master controls
- swap_surround Swap master and surround controls
- ad_sharing For AD1985, turn on OMS bit and use headphone
- alc_jack For ALC65x, turn on the jack sense mode
- inv_eapd Inverted EAPD implementation
- mute_led Bind EAPD bit for turning on/off mute LED
For backward compatibility, the corresponding integer value -1, 0,
... are accepted, too.
For example, if "Master" volume control has no effect on your device
but only "Headphone" does, pass ac97_quirk=hp_only module option.