Despite the fact that there is every possibility I am uniquely imperceptive, I thought I would throw this out there on the off chance that there is at least one other person who was stumbling around in the Vista user interface looking for a way to adjust channel levels in a 5.1 or 7.1 channel surround sound setup.
Used to be in Windows XP you right clicked the speaker tray icon and clicked on mixer, but after I upgraded to Vista I could no longer find the damn thing. Worse, something wierd in the Creative drivers I was using for my sound card kept messing with the center channel level, forcing me to go through their audio console to reset the mixer defaults.
Today I finally stumbled on it, hidden three layers deep in the audio properties dialogs. Just to prove that I really did run it to ground, here is a pic.
To find your way to the mixer right click the speaker tray icon, then click “Playback Devices” to open the Sound dialog. In the Sound dialog either double-click the Speakers device, or click it and then click the “Properties” button at the bottom. Either action will open the “Speakers Properties” dialog. Click the “Levels” tab, and then click the “Balance” button next to “Play Control”. That’s all there is to it.