I have at various times lived with Klipsch Heresey and La Scala speakers and when i sold audio we always had a pair of Klipschorns in our biggest sound room. The La Scala's were more forgiving of electronics and the listening room than the K-horns, but there is always something very dramatic about the dynamic capabilities of all the Klipsch speakers.
While I agree with using SET amps with them I also found that low feedback medium powered solid-state amps worked too, In fact, one of the nicest combinations was the Klipsch La Scalas driven by a Harman-Kardon Citation 12 SS power amp.
I have also heard K-horns after crossover modifications, and generally these did improve the sound of the speakers. However, I think the real future of these speakers is using response and room correcting devices like the DEQX. The DEQX can be used to partially tune-out the time delay problems inherent in the horns (the bass horn, midrange horn and tweeter horns are of differing lengths, so the sound waves from the compression drivers (or woofer) don't arrive at the listening position at the same time). This is a major reason why some don't like their imaging and why many feel they are "blurred" in sonic character. I also feel that equalization and other active compensation electronics (or computer software) has a better chance of working well with efficient loudspeakers than with power hungry models.
