The amp power is a non issue unless you want to cause permanent hearing damage to anyone standing at the far side of the room.
You will get more bass reenforcement from the M80's if you put them close to the wall but...
More bass does not equal better bass. Goosing the low end with a tone control will give you more bass too. From memory, the M80's have a -3db point of 36Hz anechoic. In room, that point will be even lower. That will cover 95% of the bass that is available in all music. For most music it will cover 100% of the bass, giving you a flat, neutral response. This is one area where the M80s excel.
Have you checked to see if you can find an M80 audition locally?
