I used to run the Klipschorns in kind of a quasi-bi amp up set up. I ran full signal from the pre to my Vintage Crown active crossover then separated the signal sending the highs to the Dynacos ( they are not the prettiest ) which still used the Alk crossover for the upper 2 horns. I ran everything from 100 Hz down to the Mac and let it roll off naturally. It sounded amazing!
I also had the upper horns replaced with all altec 511s which really helped. However, after going down that road I wanted to get everything back to stock and that's kind of where I'm at today. ( i used to be on the Klipsch forum all the time but got burned out ).
I really do like horns but they're very picky with gear, Lascsllas can sound wonderful with the 2a3 amp but in the end I went with push pull because of bass.
Also had a pair of bells for a while. Very nice speaker! I had the RF7s but they ended up just being too bright and to forward, never did the crossover mods to them.
My favorite horn speakers to this day is a pair of altec model 19s. They bested the altec 604s in onken cabinets by a long shot. I wish I still had these.