Even though Dunlavy unfortunately went out of business, they have the reputation of being very accurate speakers that require alot of power, so Shinerman's recommendation is a good idea. There is no problem using the Polk center and PSBs in the rear. This whole idea of matching timbre of the center and rears to the fronts, for theater anyway, is overblown, IMO. BTW, I have M60s and like them alot, although I just replaced them with Gallo Reference 3s. The M60s are now in zone 2, and they sound real good in there, even with 40' of speaker wire between them and the amps.