Thank you very much, Ralph and exlibris.
I don't really have any speakers that meet mitch2's requirements. My "fullrange" speakers go deeper than 40-50 Hz, and my "made to be used with subs" speakers cut off higher than that, in anticipation of the Swarm doing a better job than a pair of speakers can in the bass region.
For instance the main speakers I showed at RMAF last year are designed to cross over to subs up in the mid-to-upper 60's. I think they meet at least some of the other criteria though (benign impedance curve, lower-90's efficiency, drivers with characteristics that imply good dynamics). I won't make sound quality claims because who's gonna believe a manufacturer's opinion of his own products?
Duke
