Just trying to resurrect this thread and to give my input on my experience with KHorns. (FYI - Although 2 channel audio has been my hobby for about 15 years, the first time I heard a horn of any type was when I went to the house of the seller and picked up my KHorns, so I am a total newb with horns, hi efficiency speakers, etc.)
I was following this thread because I got a pair of ' 65 KHorns a couple of months ago and have been working to get them to sound their best. First thing I did was figure out that KHorns need to go in the corners. Not "sound their best in the corners" or "get them in corners if you can" but need to be in corners. Next I treated my room by taking everything out (room treatments I had from previous versions of systems) and starting over. I found that I don't need a lot of bass traps in my small room (I did with other speakers), and treating the opposite corner of each speaker with HF damping helps tame the horns.
I had planned on crossover, internal wiring, tweeter/squaker, etc. upgrades and replacements. I ran into a guy with horns and we talked about how my KHorns were (at the time) inconsistent in that some recordings sounded excellent and some sounded "off." His recommendation was to get the source and amplifier right and then mess with the speakers. I've since gone from SS and 100 watt tube amps to low power SETs and to me the SETs sound right with these speakers. I have a 2 watt (EL84) and a 6 watt (807) amp. The move to SET amps made the biggest difference to me.
I also got the Bob Crites A / AA crossovers and they helped to clean up the sound, as well as create more space between instruments. I'm still playing with the A vs. AA thing, but I'll have that sorted out soon (which sounds better to me). The Crites networks didn't make me believe I got a new pair of speakers, but they certainly made an improvement. But my crossovers were 44 years old, so I guess that's to be expected.
I've had a lot of gear in my room over the years, and I've done a lot of work and experimenting to get what I've had to sound best. I've never had a system sound as good as it does now and I'm sure there's room for improvement.
Nothing earth shattering, just some information for those who like me are wrestling with these beasts.