Heads up you cannot reliably A/B test in a room unless the speakers are in the same location. crazy Its an annoying trait of small room acoustics.

Moving the M3s to the same spot as the M60s is needed. Thats why harman has the speaker shuffler mechanism in their setup. Setting speakers beside eachother changes their loading and interaction with the room. The center to center distance of the front baffles is enough to have drastic results in small rooms. At least reverse the speaker positions and test again.

Moving M5s in my room 14 inches changed them from unlistenable to superlative. Food for thought.