Comment 43 for bug 871808

@David Henningsson: your latest fix didn't worked because default.conf wasn't the right file to edit.
Using the command "udevadm info -qall -p /sys/class/sound/card0/" on my laptop I read "PULSE_PROFILE_SET=extra-hdmi.conf", which for some reason is the config file loaded instead of the default one.

So I added your lines to /usr/share/pulseaudio/alsa-mixer/profile-sets/extra-hdmi.conf and now the subwoofer seems to be working well, after choosing the 2.1 profile that is now showing up. The subwoofer isn't playing a copy of the right channel anymore, both are played.