After installing Ubuntu 11.10, I configured my Sound Settings to be 5.1 + analog input. It works ok, but after closing and reopening Banshee, the sound channels reverts back to 2 channels, this also happens on changing the song (ie. next, previous) and also after a reboot.
The configuration dialog is still selected "5.1 + analog input" but there no 5.1 sound at all, only the default stereo 2 channels only.
To fix it I have to open sound settings and in the output tab reselect "Internal Analog surround 5.1"
Is this fixable?
I was just having the exact same problem. 2.0 to 5.1 upmixing was not working after changing the track manually on any player/program. The suggested fix worked temporarily, until a different track is chosen manually. But, fortunately i found a better and permanent solution. Try this:
Hope this works for you too.