Mojo, why do you think that I won't hear much of a difference with the M80 and a sub? Do you think that different than with the Aperion? They both have two mid-range and two sub-woofers.

I just put the system back to using one amp for a test (not an easy think the way my system is set in a cabinet). After listening intently to 3-4 pieces, I switched it back to i-amp. Maybe it's me, but I definitely hear a difference, specially with the lower tones, and "punch." I think it's because there is more power available to the high and low sections of each speaker.

It's a pain to do, but I will do the same with the M80s.

Steve