I'm wondering if the receiver line out's to the M3's is faulty. I know I have an older Kenwood receiver with an A/B speaker function and the "B" is broke.
Jerry, just to rule this possibility out, can you swap the M3's to the other output? If nothing changes, then a call to Axiom is in order. You should not have to crank the volume much to level match the M3's to your Cambridge speakers.
"......The wisdom of life consists in the elimination of nonessentials." ~ Lin Yutang