To answer your question, "I have now forgotten what the M80's sounded like", you probably just have to sit down in front of your M100's to get your answer. Since you've blocked a bunch of ports in your M100's then you probably have roughly the equivalent of unblocked M80 HP's or slightly less. Tweeter and mid-range driver layout are identical between the 2 models as you know.

Last edited by jasonw1701; 10/15/14 07:44 PM.

M80 HP v4, VP160 v4, QS8 v1 (3 in 6.1 layout), SVS PB12-Plus/2, Parasound Halo A21, Denon AVR-X4100W