In need high-efficency speakers

Markr1 is audio buddy of mine, He used to have the Zu essence , they sound very good, He discovered Omega and He bought the Alnico model speakers, When I listen to this Alnico for two weeks, I can’t listen to my system , they are so musically transparent, with live like capability, Now He traded the his old Alnico single driver, to get the High Output Alnico, this are really very very good speakers...they schooled me though...He sold his Zu speakers as well...

If I remember correctly, the Klipsch Heresy IIIs and its Klipsch cousins in that price range are a bit light on the low end. Only go down to 50-55 hz or so.

Keep the Mystere’, IMO, that should be the anchor of your system, as you are.

I have had a pair of Zu Omen bookshelves for 2 years, and have run them with a pair of DIY Tube mono blocks that I built. They are a good design, but nothing groundbreaking, 40 watts, but the Zu’s sing like a bird with them.

I have NEVER heard anyone say that Zu’s are thin and veiled. Thats just silly sh*t. Check your amp, source, and cables, yo. You are bottlenecking your system somewhere in the chain before the signal gets to your Zu’s.

OP: the Zu’s are "designed around the human voice" and made for "live sound". Read their website? This just means that the SQ has a natural and real presentation.  Zu’s of course are crossover-less designs, so they are fast, nimble with excellent dynamics. But the midrange is gorgeous b/c of the "designs around the human voice" especially with the tubes. 

IMO, Zu’s were made for tubes, you will get an organic sound with very good soundstage. I also own a PrimaLuna HP Integrated, and of course PrimaLuna and Mystere are made by the same company, so I understand the sound you have. 

I would recommend the Dirty Weekends, they are one of the best deals in speaker audio. Run them with the Mystere, and I think you will have a smile on your face. :) 

Lastly, I recommend calling Kevin at Upscale Audio (he is part owner of PrimaLuna and Mystere, ya know?) and asking him to recommend an efficient speaker for your Mystere (which of course he also sells). 
Best

Zu is special  hate  and love product. Some say too harsh and thin,
Some is best product ever been made. 
I belong to first group 

Anyone buying Heresy IIIs should look around for a REL sub, as I've found these to match really well with these (and other) speakers, and in the last few years found a couple of great used RELs for a couple hundred bucks each. 

I heard the Zu's with jazz funk being played at a show, and they did not sound at all convincing to my ears. They were on the longer wall in the room at the show, so maybe not the best or Ideal position for them?. *If all you listen to is the human voice and Gregorian Chant then more power to your elbow.   *smiley face.........
Seriously though, well respected UK hi-fi reviewer Jimmy Hughes for
HI-Fi +?  reviewed them with great enthusiasm with a very complimentary review, he liked the Klipsch sub (12") woofer he was using to add musical depth with the III's also.....
I missed out on a local sale of a virtually new pair  of III's going for $1000.