The best speaker you ever heard?

Proac D38. Or other Proac models (D25, Studio 140) depending on your budget. Very very musical speakers. Makes you want to listen to music.

Since this thread is still going strong, will chime in from my recent discovery.

Usher BE10/20, incredible reproduction of minute details and leading edge dynamic that are hidden in most speakers. Superb integration of tweeter and midrange due to similar material used (Beryllium) and close proximity physically. Able to play loud despite only having one tweeter and one midrange per speaker, this has the advantage of reproducing more focus sound unlike those multi tweeter/midrange speakers. Excellent bass, beautiful craftsmanship, and sexy real wood cabinet.

I also like Analysis Omega (superb transparency and coherence like Apogee), Elac top of the line model (excellent top to bottom, though a little soft), and MBL101E but not with MBL amps which produce too much bass output.

Semi, have you heard the Pioneer SX speakers? They use the midrange and tweeter drivers from TAD, owned by Pioneer. I heard them at last year's RMAF and have thought seriously about buying a pair. They cost $9500 per pair!

The speakers from Classic Audio Reproductions also utilize TAD drivers. They have several models, and at least one or two below $10k.

Ralph Karsten of Atma-Sphere owns a pair.

Tvad, you may be right. Long ago when John was still just redoing existing Hartsfields, I gave serious attention to them. I guess I just like Altecs more and don't like the lens concept. A friend has always insisted that the Paragons if raised 18" off the floor on a solid platform are the best speakers, but to my listening they sound too diffused almost like Boze speakers.