I am using a down-firing Yammie with the M3s that I got for $50. It's very good for music. Whether you use the M3s or M5HPs for music, a sub makes a nice difference - particularly for the M3s. I also listened to them extensively with my beloved 800v4 in my main room and the blend required no tuning whatsoever.

I've set up an M3-based living room system that was on my mind for the last 5 years. I have the M3s 4 ft away from the front wall, 20" from the sides, 8 feet apart and the MLP 8 ft on the diagonal. I'm sitting well-away from the back wall; maybe too far because I'm in the middle of the room. I'm driving them with an old Denon that doesn't have room correction. I have a long way to go to tame the room. However, the v4 soundstage is unmistakable. It's nowhere near as spectacular as my main space but the depth, width, height and image focus is characteristically v4.

I shake my head with some of the comments on the boards that Axiom hasn't innovated. Axiom burned the midnight oil squeezing everything it could with the current architecture out of The Family of Curves. It shows on the v4.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated