What does one purchase after owning horns?

Soundlab ESL speakers are what you may be looking for. They are a point source speaker with perfect top to bottom integration.

This will most likely require an amp change also however.

Watch for a pair of Duo's or Duo Omega's.
The Duo's main horn goes deeper than the Uno's.
I almost gave up on the Duo Omegas that I purchased.
My room has a terrible hole in the 142Hz - 160Hz region.
Right were the horns and subs integrate.
I just could not get the bass right.
I tried reversing polarity on the Sub225's but it did not help.
Tried endless positions.
Then I bought a used Behringer DSP1124P parametric EQ for $80.00.
Ran a second pair of outs from my pre to the EQ then to the XLR inputs on the Sub225's.
I have a Behringer DEQ2496 that I use solely for RTA use.
A total of 3 left and 4 right parametric filters took me from listening hell to listening heaven!
If horns are off of your short list, I second the Sound Labs.
But keep in mind, that it may be the bass response of your room, not the speaker.

If you could go up a bit in budget the Audiokinesis Dream Makers would be worth looking into. If you prefer something more conventional then the Jazz Modules might work for you.

Large active ATC's or PMC's used will do the trick of integrating bass and sounding dynamic and articulate like horns.

As an owner of Tannoy and Soundlab, htey are very different beasts. Both have the seemless single driver point source sort of sound that I adore. They both also have weaknesses.

Tannoy- PRaT and dynamics! Smaller imaging and less resolution (unless perchance you can go way up the chain).

Soundlab:Resoultion and imaging are first class, but I am always fighting for more macro dynamics and swing.

I am very curious about the Audiokinesis line as Duke was a Soundlab distributer.