Horns with good timbre and tonality?

@audiokinesis --

Thanks for your insights and pointing to actual mechanisms that to you are vital to achieve a more natural timbre. 

(addressed by you to the OP)

You mentioned full scale symphony. The ability to convey the hall ambience on a good recording again goes back to getting the reflection field correct, as the in-room reflections are in effect the "carriers" for the reverberation tails on the recording. I can go into more detail about this if you’d like.

I'm certainly all ears for an elaboration here. 

@audiokinesis --

Thanks for your elaborations - very illuminating.

In your previous post, on which horn type in particular could facilitate a proper reflection field, you wrote:

... Ime what works well is a constant-directivity horn which does not rely on diffraction. Most horns do not fit this description.

What about, and maybe when is the diffraction part most troublesome here; what’s inherent to - as a distinct sonic imprinting/coloration - the narrow slot section leading up to the horn widening at every volume level (i.e.: at lower levels as well), or more predominantly at higher, and perhaps only very high SPL’s? My understanding is it’s more the latter than the former, which urges the more pragmatic question of relevance in a given, domestic setting when, or rather if the issue seems to arise only at, say, +120dB levels.

I find horn size to be a factor as well, certainly with a lower crossover point and trying to maintain a fairly uniform dispersion pattern at the crossover with directivity control all the way down to the crossover. My finding here is that, generally, the larger the horn the less it sounds like a horn, and by that I mean a more relaxed, properly (i.e.: realistically) sized, dense and visceral sphere of sound. What are your thoughts on sheer horn size here?