For me, when I used a AVR receiver, I would play music with what ever setting I wanted that sounded the best. There are not rules. It was fun for live performances to use all 5 channels or at least 3.1. Usually though, just 2.1. Now that I am just 2.1 (or actually 2.2) with no AVR, there is no center channel for music. The imaging takes care of it all to present an audible soundstage.
Who turns center off when listening to music
Regarding 3.1 systems. When listening to music; Who deactivates the center channel via the processor?
And with surround systems who goes back to 2.1 when listening to music. Do any of the processors have presets you can you for this?