Boy Rich, did you start something here. My Audio Source amp will be connected to my rear M3ti's on Tuesday. Will it make a differece in "headroom?" You bet it will. My tube amp is connected to my mains (M22v3.) Does it make a difference? You bet it does. Now my h/k AVR 645 has only the center and surround channels to power. Do the math here!! Adding a separate amp to relieve the AVR of other duties makes sense.
Tech. measurements not withstanding.