It would be tough to "improve" on the sound while stepping sideways in the same price bracket. You may get a different sound, but those are excellent speakers for the $. If it were me, and I were looking for something different, I'd look at Coincident (which I own) which would probably offer a more detailed picture rather than the slightly warm, rounded qualities I'd expect from the Sonatas (and I only mean that in a complementary way). Also Merlin. I'm assuming that you need to stick to something in the more sensitive range. There's also Reference 3A's flagship which sounded really great in several rooms at CES and RMAF....I think it was the Grand Veena. Plenty of others in that price bracket...of course look for something that suits your amp(?). If you don't need sensitivity then that stable of options increases in size dramatically. Another superb option in the more sensitive offerings would be Daedelus, though you may have to pony up the bones as they very rarely show up used. That certainly would also give you a very unique change in appearance. Lou's joinery is second to none - his speakers have a very hand made fine furniture look to them, in a very traditional sense. They are made entirely of solid woods. They are outstanding speakers which I've heard several times, both at the shows and at the Modwright showroom.
Have fun!
Have fun!