The one meter SPL test is interesting...I guess. But is your seating position at one meter? (I get the spec sheet comparison, but don't think you are using this info correctly.) Test the SPL at the seating position. My Denon 3300 begins to clip at 0.035 distortion at 84 watts (if I recall the test sheet right). My PSB towers are 4 ohms, and I can get clean sound at 105dB. Not at one meter, but at 12 ft. In short, your in depth tests are hard to compare to real world use.

The problem, if any, is not the M80s. There is far too much written on them, and users here, based on well over 150 watts (the real kind, not the advertised kind) in normal use to blame the M80 for the lack of output.

Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire