Roger,
Youe last comment/question is mostly true. Running two pair of (identical - equal sensitivity) speakers very close together (i.e. side by side) generally, would increase your SPL (volume) by about 3db (everything else being equal)- as that configuration produces an additive process to the loudness - and thus you could drive your amp at a lower power to achieve the same "loudness". However, a 3db change is considered only a "noticable change" in volume. (It takes a change of 10db to be considered twice as loud) Dispersion would depend on how you "aimed" the speakers and imaging would be diminished - but somehow, I don't think that is the issue. But if you stacked the M22s exactly alike on top of each other, you could minimize the imaging loss.
Good luck,
Randyman
