Thanks for the replies. Had a feeling there would be such a setting but knowing what I was looking for allowed me to find it.
One follow up question: I know it is possible to adjust the levels of each speaker. Is it possible to have the receiver save your preferred levels to a source like it can save your listening preference (all channel stereo, stereo, Dolby EX) to a source?
I'd like to turn down the rear channels (but have some sound) while watching all channel stereo TV but have them back up to their full levels for DVDs and games.