My experience with the K-horns has been surprisingly positive. I think they are actually rated to 35hz (not that it matters). It seems that a lot of people drive them with solid-state these days (not me though).
They are not flawless, but on orchestral, they can be incredible. They have that "just breathing" sound that big horns have. The dynamic range is just astonishing, and for some, it might be too much dynamic range. I spent a couple years tweaking everything and that was a long road.
I am still using a little wideband ("fullrange") driver for non-orchestral, and of course it can do many things that the K-Horns can't (e.g., you can sit closer, they disappear on certain tracks, they image better, they have that sweet coherent sound that many people instantly love, and on many things, the tone is better, e.g., you simply cannot tell the difference between them vs. live sounds like phones, bells, knocking etc.)
