Klipsch K Horns (the new AK6)

High efficiency and load are of course two different things.

Getting a good match is always critical but the speakers that will work well with the widest variety of amps are those with an easy load, like Daedulus and Fritz, not necessarily those that are high efficiency.

Efficiency only determines how loud things can get per watt.

An easy load also means "better mileage" per watt which can translate to speakers going louder better than others with difficult load yet similar efficiency specs.

High efficiency speakers often get a bad rap because they have potential to easily sound the most wrong if not driven by the right amp. But with the right amp....... Not for the faint of heart.

Had a pair of LaScalas in a huge living room powered by a custom made SE EL84 amp from Don Allen- RIP. Kicked a-- on anything from solo guitar to jazz trios to symphonies to rock. FWIW.

mapman,

I dont disagree with anything you wrote, but often it is the higher efficiency speakers that have a higher and more stable impedance curve for use with tube amps. 

Bad measurements for sure, but they sound very good. I know because I owned a pair for years and used both tube and SS. No surprise that georgehifi started a thread trashing them. He's a well known horn hater.
By the way George, you should learn when to use "their" and they're".

Perhaps you people that have never actually heard the speakers in question but give your comments freely, should listen first.  Anything you say if you don’t is merely speculation on your part and isn’t helpful. I have heard many products that measure poorly yet sound incredible.