Comment 39 for bug 1203520

Ubuntu 13.10 Saucy Salamander beta 2 neither working well with nouveau nor with nvidia-319 per https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1203446 #36 et seq., calling the beta a "fix released" (in particular to an LTS) may be premature, even though no crashes have been detected yet on Saucy in further testing of HDMI audio with the latter proprietary driver either, and after installing pavucontrol from the Universe repository.

Neither System Settings / Sound (which will not switch back to 5.1 from a 2.0 speaker layout, and keep the 5.1 speakers silent even if shown) nor pavucontrol (which does not have HDMI audio in the left tab's drop-down at all) offer a usable selection (and testing option) for the surround output on Saucy anyway as of yet, so this is limited to command line use with speaker-test -c6 and the like at this time.