My room is roughly the size of yours and I use M22's and an EP350. I wouldn't go much bigger with the 22's as far as room size and I occasionally think about upgrading to the 60's. I'm sure you won't regret gong the M60 route. The EP500 will have more than enough boom for your room. My 350 handles my room with power to spare. The 500 will go lower than the 350. I've seen nothing but good posts about the 500 from owners on this forum, after they get it placed and calibrated correctly.

"That's some catch, that Catch-22." "It's the best there is." M22ti VP150 EP350 QS8 M3Ti