The best speaker you ever heard?

For me, the dynamic and slam is the taste. Thus the Montana KAS tower speakers by PBN(Peter Noerbeck). Boasting 7 way system per side - twin 12" woofer, dual 9" mid's, dual 5" upper mids, and a tweeter in vertical array(dapolito). All scan speak components. Weighs in at 300 lbs per side. 4 monoblocks of 500 watts amps will produce bigger and better than live event.

Apogee Diva's 20 years ago at a HiFi show in London. I can still remember the incredible lifelike sound reproduction. Well, at least I think I can!

I can say with no doubt, that the Green Mountain
C-3 is the best speaker I have ever heard anywhere.

More later as they break in.

Nautilus 800 and 801.
There are always trade-offs in any speakers that I listened to. Some have 99% imaging but 85% in freq range Some have 99% transparency (like logan) but lacking in dynamic, some has good low level details but sound compress when played loud.
I like the Nautilus 800 and 801 because they score 95+ across all spectrums (excellent dynamic, imaging, details, frequency range and transparent).

Avantgarde Duo's - I've heard a lot of speakers, but nothing has made me "Enjoy" listening to music like these horns with a great SET amp. Set-up is critical (heard good and bad ones), but when done right, these are absolutely magical - foot couldn't stop tapping. I can't wait to hear Trios, although I might sell my car to buy them if I heard them.