Some solid state amps operate in Class A up to a certain point, which is said to be close in some respects to the sound of tubes. I have a solid state amplifier that puts out 250wpc (Class A/B), however it operates in Class A mode up to 25wpc. I'm curious if this amplifier, operating in Class A mode, would be a good match for a high efficiency horn system.
My active speakers operate in Class A up to two thirds power (i.e. 99% of the time I listen to music) I would not characterize the sound to be like tubes at all. There is no characteristic tube warmth in the bass and lower mid (from harmonic distortion), even at high ouput levels.
I can still hear tube warmth when playing music that has had some of the recorded tracks deliberately run through "tubes" in the mix or mastering studio. Tubes are a great tool on dynamic instruments like drums as a form of compressor; the kick drum heavy thud sound is a charateristic of tube effects often applied to modern rock recordings.
Myself, I prefer hearing closer to what the sound engineer or artist intended rather than adding my own seasonings. Although, I completely understand people who add seasonings to taste, just as those who add salt and pepper to a meal. (after all you eat the food - so why not add some spice!)
I suspect the tube and horn match is a marriage born from the necessity to have a more efficient speaker for tube systems to achieve high SPL levels (rather than horn aficionados all wanting tubes). So tubes lead to horns rather than the other way round.
So I see no reason that you should not continue to be perfectly happy with your SS amp when connected to horns...