I own a pair of M3's that are used in a large basement. Up until recently, I was powering them with a Denon DRA-685 receiver. I love the M3's, but I do feel that in a large room (at lower volume levels) they need a bass boost. The Denon receiver has a "loudness" button which boosts the bass at lower listening levels. Some audiophiles will "cringe" at the thought of using the "loudness" feature, but I found it added immensley to the sound of the M3's in a large listening area. If you don't have a loudness feature, have you tried increasing the bass with the tone controls? Again, some will say you should always listen with the tone controls flat. I would try it and see how it sounds. My speakers are currently about 24" from the back wall. Yes, moving them closer to the wall gives them more bass, but at the expense of better imaging and soundstage. I'd play with the tone controls and see if that helps. Also, do you get better bass response when you turn up the volume, or is it lacking at all volume levels? Good luck.
