what do horns sound like

Ive probably only heard one or two many years ago and i may never get a chance to hear another anytime soon.

Do they work with pop music and electronic music? 

Do they disappear?

Do they have even tonality?

are they for nearfield or far field?
" The active/passive/eq question will require some doing; I'll try to condense. "
     That's a lot more complicated than I will ever get. I feed my signal from my PC to the Xilica and then to my speakers and call it a day. One thing I did do that was very simple and many are not aware of is to upgrade the stock sound card. On my Dell workstation there is a realtek sound card which is pretty plain jane as it is. You go to the Realtek website and download the High Definition driver and all of a sudden it is a 192ks sound card with great fidelity. I know there are a ton of things out there that are possible improvements but I am satisfied enough with my current system that I am not really looking to find one.
Hi Duke, intentional diffraction isn't always a bad thing. I've had a pair of EV 8HD diffraction horns for years, though no longer in use. They have no edges but do have a narrow mouth (and their literature is where I got the idea of damping the edges of horns not surface-mounted!). JBL had diffraction-slot loaded biradials. Anyway, all that said, the 150 (sort of a tiny mantaray) has its ups and downs, but I never saw irregularities like odd harmonics on tone tests, so I took some advice on having compatible dispersion patterns. However it goes, it's amazing what you can find for very little money these days, isn't it?
@mahlman, it's always good to be happy with what you have, but I hope you'll take another look at what you can do with that computer and a ton of cheap/free DSPs. Certainly took me a while to get the hang of it, but the world is at your fingertips.
"Hi Duke, intentional diffraction isn’t always a bad thing... I never saw irregularities like odd harmonics on tone tests..."

Diffraction doesn’t show up as odd harmonics; rather, the spectrum of the diffracted signal would be a significantly distorted version of the original, much lower in level than the original and arriving after a small time delay. Ime its effect on measured frequency response is negligible.

"... so I took some advice on having compatible dispersion patterns."

If the cost of good pattern matching is having a little diffraction, I’d probably make the same choice you did, unless listening tests said otherwise.