LaScalla "horn" sound compared to "maggie" sound

I went from planars to horns back in 2006, sort of the reverse process--though it was Quads, not Maggies, and Avantgarde Duos, not Klipsch. So, I can't speak to the specific speakers you are talking about (though I played with Maggies many times back in the day), I can tell you about my experience in general. The horn speaker, for me, was more persnickety about everything upchain--and the SQ varied dramatically based on the rest of the system. Midrange was comparable to a good stat, but with a far more "in the room" quality and that so-called "jump" factor.  Same issues of bass lightness or discontinuity as stats when it came to mating woofers- of course, the original big K-horn solved that by corner loading. Size of image- Maggies present huge. It's fun, great for large scale music, my recollection was that they didn't have the pinpoint imaging that stats did- though more modern Maggies with ribbon tweeters and judicious set up may improve that. Horns- you don't even care about image, as such, because the of the "in the room" quality. --'Tis fun to have both. I just got my old Quad '57s restored. My horns are in storage awaiting a new room. 

I have owned MG 1.6 (powered by Bryston 3B) and LaScalla (powered by Audio Research VSi55). I liked both speakers, but as someone mentioned, they are very different animals. I don't think you will be satisfied with the large Bryston powering the LaScallas. My guess is they will be forward and bright and harsh. You are better with a small tube amp or even an old Marantz receiver (I also used a 2215b and it sounded good although not the final word in resolution). The Magnepans provide a transparent sound that makes instruments sound "real" and the LaScalla will definitely impart its own characteristics on the sound (not transparent) and instruments will not sound as real. Don't get me wrong, I do admire the Klipsch heritage speakers and presently own a pair of K-Horns and Belle's. I enjoy listening to them with jazz music because the horn reproduces a horn instrument (Trumpet, Sax) very nicely and the sound is very dynamic. However if you want an acoustic guitar to sound like it is in the room with you, the Magnepans will do that but the Klipsch won't. Again totally dependent on personal taste. Good luck with your decision.  

I powered once LaScalla with Pioneer SX626 solid state receiver and it seemed to be a very sound match

if horns, then first watt