Since hearing them, I've only ever owned MONTANA. Everything I have heard subsequent to those acquisitions has confirmed that choice -- and when I say "confirmed," I guess I should say, I have been shocked at what others are paying good money for -- even internationally well-reviewed speakers.
Shocked.
I think I do know something of the difficulty in pairing them with amps though. These speakers are D E E E E P. Meaning that they can get right into the gut of an amp, tap it, and turn it inside out. Blew up a few amps getting rock concert volumes with audiophile sound. Speakers never quit, amps did. Experimented with Bryston -- pretty superficial, meaning maybe not getting to the performance MONTANA is capable of.
Like the Mac 501 suggestion -- perhaps the best overall performer with my KAS'. Not the most awesome vibrate-your-spleen-with-perfect-control bass however. Krell will show you what kind of bass these things can give you -- toss the subs -- but not enamored of the Krell sound, so went with Plinius. Bass almost there, but much preferred the Plinius sound through the spectrum. If you want zip, clarity, transparency, presence, loudness, bass control -- Plinius 102, or even the 100s.
Something might seem sluggish or rolled-off with the Macs versus that kind of pizazz, but that's what I have settled on -- very rich, full-bodied musicality there. Also have a pair of Parasound JC-1s that I listened to for about ten minutes -- due to moving, have not listened enough to give any testimony there.
Hope that was helpful.
