What Horn loaded speaker/ speaker system for $10k'ish and under

I've heard and liked Volti and also Charney Audio both have speakers in your price range.

I am a horn speaker fan, but the really nice stuff is considerably more costly than $10k.  But, the Cornwalls can be quite nice with the right tube amps.  Something like the Volti Rival is nice too.  Although not a conventional horn system, I’ve heard the single-driver (back loaded quarter wave) Charney Audio systems deliver terrific sound; I heard the Companion system which is way beyond your price range, but the sell less-costly models.   

Spatial audio labs they use the very good Beyma Big AMT horn tweeter-midrange 

and dual 10 or twelve inch drivers and a very refined open baffle speaker over 92 db and right in your price range, and 45 day home  audition.

There was a listing posted 2 days ago for a pair of JBL L200b's for $4500.

I have a pair of JBL 4349's in my main 2 channel listening system which use a 12" woofer and their relatively new waveguide design with a 1.5 inch compression driver for high frequencies.  I thoroughly enjoy these speakers and the high frequency response and tonal qualities of the waveguide are delightful.  They have no harshness and are not bright.  Smooth response, great soundstage/imaging and are very detailed cabinets.

Low & mid frequency response of the pulp 12" is also very good, though I cross over at 70 hertz to JBL subwoofers.  The few times I've used them while bypassing the subs, I've found the 4349's to have nice, detailed, firm bass response and may be more than adequate for most listeners.

I'm powering the 4349's with 300 solid state watts per cabinet which is more than enough for how I use my system.  Finishes include walnut along with the usual black.  Very heavy at around 80 pounds.  Sensitivity is 91 db and list price is a bit above $8,000 for a pair.

I feel that some of the Klipsch Heritage series cabinets have much more of a traditional horn and live sound to them vs. the JBL 4349's.  JBL did their homework on the waveguide to make it not sound like a horn though high frequencies will extend into the room with great effect.

I have a decent sized listening space and wanted a system that filled the room more than a smaller/traditional box speaker system could.  The 4349's (and associated subwoofers) really fill the room at moderate levels and should I wish to really make the amps work, the system can reach nearly crushing sound pressure levels. But they also work very well at low listening levels.  I enjoy most all genres of music and the 4349's are effective on most anything I listen to.  As you can probably tell from my rambling, I really love these cabinets.

While above your suggested price range, the aforementioned JBL M2's and 4367's are also great choices (M2 being the flagship waveguide loaded cabinet).  The 4435's are a cool old school JBL cabinet that were well regarded in their day, not just in the studio, but at home too.  The single 15" woofer 4430's could be another old school option for typically less money, though they do not have the low frequency "oomph" that the dual 15" JBL 4435 has.