These guys sound a lot more scientific than I am...so I'll keep my concerns simple. Your distance between the speakers may not be enough. I believe in my time here learning it's been widely discussed that the M60's need a decent amount of space to breath. I THINK (that's as far as I'll commit) that a minimum of 8 foot is ideal so you might be pushing your room setup with the 60's at only 6 feet. You might want to do some thread searching to make sure I'm not out of my mind. Either that or contact axiom themselves. They could tell you for sure.
Good luck! Congrats on the impending purchase.
-Nick
