Here is my audio panel with 5.1 sound enabled. I use the CD_in for my AIW TV card sound and I have to adjust each of the channels individually if I want to totally turn down my DIVX movies. I even wrote VIA and asked them to put a master volume in there for the next driver release. They wrote back and said that the WAVE control serves as a master control. WRONG! It doesn't do squat to some audio sources, like my AC3-encoded DIVX movies.
The entire audio panel would have 14 sliders for the following in this order:
Front Speaker, Wave, SW Synth, 3D Depth, Subwoofer, Center, Rear Speaker, Mic, Line In, CD Player, Video, Aux, Phone, PC Speaker.
EDIT: Notice that the "Front Speaker" slider is in the high ranking position where all "Master Volume" controls should be.
The ones I use are: