Not having a matching center that worked for me was one my decisions to send M80s back. The 150 sounded like it was in a tunnel.
I also found for me the 80s distorted around 93db- 96db 11ft away and never use to notice lights dimming on AVR at higher levels (or the room lights). The bass in the M80s is great, the detail almost same as my Klipsch, little less.
For the price they are a good speakers, just wasn't a $1,700 difference in sound going from my low end Klipsch which retail about same price as Axioms.