I was just browsing this forum for the same problem.
Burning fantastic, but sound is poor. I have to adjust my DVD-player/TV volume from a normal 23 to about 55 to hear any sound.
I also use high quality original blank DVD's. Burning is done on 3 different computers with each 2 (new) DVD burners.
Just to check what is wrong, I have used a different program to burn a couple of DVD's. The problem
is gone. I got sound with an equal volume to that of my DVD-player/TV volume.
Am I missing something in the answer of Lightning?