In SMPlayer or VLC you can change your Audio to use different outputs/settings.
In a root terminal screen (Ctrl-Alt-F2) Old Sounblasters are initialyzed by:
They are not all available anymore, for you to check one by one....
setting up the card with
Go back to your Graphic screen with Ctrl-Alt-F7(or F8) and check your audio.
if you found the right one you can add (as root) sb, sb8, sb16, or sbawe to
not playing sound from divx
But you have sound allready, maybe missing
Install from Synaptic