Comment 3 for bug 642230

> Does your machine physically have 4 output jacks
Yes.

> have you selected the correct output profile
There is no 7.1 there. Attached is a screenshot of what's there.

The way I confirm this is an alsa bug
speaker-test -Dplug:surround71 -c8 -l1 -twav
plays only front left and front right.

It also worth mentioning that I need to kill pulseaudio or use alsa directly from applications to be able to hear any thing.