Who turns center off when listening to music

My systems are 100% independent of each other. 2 channel and ht do not mix in my home. Many people have mixed them with ht bypass are are very happy but I have made my choice of having two totals separate systems and am very happy.

Yeah I have a much more robust main 2 channel. Just started assembling a modest AV setup just to watch concert vids primarily. Found a good deal on nice center channel and added that. Then upgraded the left right speakers to some Dynaudio. Put an old Sonos zip 90 modified by W4S , a good DAC that a friend gave me and fiddled with settings in the Denon AV and dang I’m surprised how good it sounds.

if I was in a different income bracket and  the  room didn’t suck I could see collapsing it all into one.

Wait, what? NO!

I have a combined 2 channel / HT setup. The AV processor is OFF when listening to music. No need for a center channel.

Conversely, for casual TV watching, I often don’t use the two front speakers, just the center.

With  stereo sources you shouldn't have the center working unless you are deliberately picking to use it by having a theater processing mode active. Personally I like the Neo6 music mode, but don't really use it.

I use the center channel all the time for everything. I listen almost exclusively to 2 channel recordings and up-mix everything to 3 channels with simple channel summing and subtracting - no complex processing. The 3 speakers are very close together, on 1 foot centers. This creates enough crosstalk reduction to restore a normal width stereo sound field while completely eliminating the comb filtering caused by the phantom center image created when using only 2 speakers. Anything panned center will only play through the center speaker. The speakers are all far away from the side walls, and all close enough together to have a similar acoustic interaction with the room and thus create a cohesive sound. I think one of the biggest problems with center channels in normal use cases with wide spacing between speakers is that the center speakers are loaded into an acoustically different space than the side channels so they don’t blend in as well as they should, even if the center speaker is identical. A wider spaced 3.1 system might work better in a wide room, where all 3 speakers are a long distance from any corner position. My limited experience has supported that notion.