"1. Edit the PulseAudio daemon.conf file by pressing
Alt + F2 and enter:
gksu gedit /etc/pulse/daemon.conf
"And search for: default-sample-channels. Remove ";" from the
begining of the line, and instead of "= 2", change it to the number
of speakers your system has. For instance if you have a 5.1 system,
the number should be 6, for a 7.1 system: 8 and so on."