high-efficiency loudspeakers

+1 for ZU Audio. I have the ZU Audio Soul MKII's and they are 99db efficient. You can drive them very easily. They are very fast and the midrange is terrific. You do need to take time with speaker placement (as you would with many speakers.) Also, points for WAF if this concerns you at all. 

I had a chance to visit ZU Audio in Ogden Utah in April 2016. The team couldn't have been any nicer. They gave me a tour of the facility and paint/cable assembly rooms and they made a clarity cap/Juniper bypass for me on sight (which was easy to install when I returned home.) 

As mentioned previously in this thread, if you want analytical, ZU will not be for you. I would keep with ZU if I decide to upgrade (to the Omen Def MK4) but I do not see that happening anytime soon. 

Good luck

Did anybody listen Tribeca-001 by bache in NY audio show?

I've been a huge fan of Deadalus Audio speakers for over a decade. During that time Lou has steadily pushed his designs forward in terms of performance without losing an iota of what makes his designs some of the most musically compelling loudspeakers you can get at an price. They are all very high efficiency (96db+) with a very flat impedance curve so will work well with a wide range of amplification. I recently heard his new Apollo series design (Apollo 11) and was stunned by their performance. For high efficiency speakers Daedalus get my strongest recommendation!!

Ralph is there an established price list for the "Classic Audio Loud speakers" ?

It depends on which model and which options. So they can be anywhere from $8000 and up. I've not seen an established price list- just give John a call.

@dodgealum , while the Deadalus is a very nice speaker (and easy to drive), its not really what I would call 'high efficiency' although they are at the high end of what seems to be 'moderate efficiency'. He specs 96db+ on his site, but that is a sensitivity rating, not efficiency. The sensitivity rating requires that you take the impedance of the speaker into account because the rating is based on voltage rather than power.

So for example, if the speaker is 96db and 6 ohms, its actual efficiency is around 94.5db. 97 or 98 db might be the bottom end of what is considered high efficiency, with many examples being over 100db.

@bache

What is the best high-efficiancy loudspeakers? If you have it, are you happy ?

Don’t know what’s the best out there, or to whom, but some of the better of the crop true high efficiency speakers (>95dB or, as suggested by poster atmasphere, even >100dB’s) could be something like Living Voice’s all-horn Vox Olympian + Elysian (horn subs)/Vox Palladium + Basso (horn sub), or Oswalds Mill Audio Imperia all-horn system (incl. horn subs) - all of which sits at 105dB efficiency, indeed what I’d call very high efficiency. These speaker systems cost a fortune, certainly the Living Voice iterations, and are what I’d refer to as statement products.

However, there’s a whole range of perhaps lesser known and generally much more affordable "sub-genre" of horn speakers, if you will, that also includes vintage models from Klangfilm like the Bionor, Euronor or the massive Eurodyn (hardly for domestic milieus), Western Electric models such as the 12a and 16a, Shearer horns, RCA, etc. and variety of DIY options - speakers that in some respects can (more than) hold their own against much more expensive, contemporary (and more readily known) brands and models. To achieve the fuller sonic potential I’d go all-in and opt for all-horn options (rather than hybrids), size and other practical concerns be damned; if you’re going after high efficiency don’t be coy or apologetic, and be prepared to re-think speaker-amp configurations completely.

My own speakers are Simon Mears Audio all-horn Uccello’s. They sport an efficiency of a measured 105dB, and are based on the Klipsch Belle model (apart from a slightly tweaked bass horn flare everything else is different, and better, and the speakers are hand-build by a true artisan from scratch). And to answer your question, yes, I’m happy with them - very much indeed. I suspect in the future to wring even more potential out of them with a 300b-based SET (~7 watts), build by an associate of Mr. Mears who’s very knowledgeable with the sound of the Uccello’s, and possibly - if practical circumstances permit - the addition of a pair of horn subwoofers (build by Mr. Mears) in the future as well. As is they are very capable in my setup, and gather I’m off the merry-go-round in this department for years to come.