What is it about the horn sound you prefer? Directivity, dynamics, efficiency, or the :horn" IM?
Have you considered something like a older Gedlee that used a compression driver on a waveguide, sort of a horn? Also used a PA style woofer. Or the new Purify large wave guide speaker? Neither of these will work if you have a 12W tube amp though. They will give the kind of dynamics you may be looking for but much flatter response and lower IMD.
Personally, I consider horns only useful for PA. Places where the SPL and efficiency overshadow DR. Great we have so many choices though.