I briefly used my VSM SEs in a similarly sized room. Backed up within 2 feet of the wall, the tonal balance actually improved - and quite significantly. The trade off was some loss of pitch definition in the bass and deterioration of the otherwise world class imaging. I don't know the MX, but I doubt it would overload the room. But if you do find the bass too prominent, simply pull the BAM from the loop. When you move the speakers to bigger digs - move them out into the room, reconnect the BAM and enjoy.
Marty
Marty