I've had some sound problems in MX-15 with VLC and Trinity.  The issue 
is solved... sort of.

This is a link to the discussion:

  http://forum.mepiscommunity.org/viewtopic.php?f=100&t=40197

The short version is:
After I installed KDE Plasma Desktop, the problems cleared up. 
Recently, they started again.  If I log out of TDE, log into Plasma 
Desktop, log out of Plasma, then back into TDE, I have sound again in VLC.