Are they worth $7k new, and you would still have to add the mods?
I think you're referring to the brand new K-horn. I happen to prefer the heritage model. Ours were built in 1978, and we purchased them from the original owner.
Only one $58k speaker that would replace your big Ks?
I'm amazed as much as anyone is, yes. And I go out and listen to 3-4 systems per month, and for the past several years, in fact. In people's homes, dealerships, audio shows, etc. Not with the intention of coming home a winner, but rather with the intention of finding our next speaker. Yet, nothing hits me in the gut like music through the K-horn. There is a sense of expansiveness to the music, and an absence of restriction in the midrange that I find lacking in many other speakers, no matter what else I like about them. The K-horns reproduce music at a life-like stature, so that all of the instruments have a presence that is commensurate with what you know them to be. But again, they are not simply plug 'n play. A few minor tweaks, however, and they are outstanding. Pair them with a good SET amp, and you'll hear the violin playing in the room with you.
Allsmiles, a good tube preamp will elevate your system to a whole new level. Definitely worth trying them. And again, if you would state a budget for a CDP, I'm sure people could help you with your choice.