In need high-efficency speakers

Considering that i have owned hereseys and cornwalls, i am personally much happier with 3 different pairs of coincidents.  The horn tweeters get old....
Also, coincidendts have much better WAF and i get better imaging due partially to the smaller footprint.
Anyway, it would take quite alot to get me to ever own Zu.  Made my ears hurt for a week.

Check out Decware speakers. Talk to Steve there (owner and designer) and tell him your details. He'll advise you. 

Disclosure: I do not own Decware amps or speakers. But I did spend a happy listening afternoon in the Decware workshop. 

A question for the OP: When you say that you can’t get enough volume with the combination of your 40 watt amp and 87 db speakers, is the symptom (a) if you turn the volume control up past a certain point you hear clipping distortion, indicating that the amp can't supply enough power, or (b) you simply run out of range on the volume control, and at its maximum setting the sound is undistorted but is not loud enough, which would signify a gain problem rather than a power problem?

One reason I ask is that the 30 db gain of your Mystere integrated amp is on the low side, for an integrated. Another reason I ask is that as Audiothesis stated earlier "40 watts will get you around 103 db at 1 meter and that isn’t anything to scoff at." (And that is from just one speaker, not two. Although it assumes that the specs on the amp and speaker are accurate. Also, at distances greater than 1 meter that volume will fall off at 6 db per doubling of distance, neglecting room effects).

All of which leaves me unsure as to whether the problem is not enough power capability for your 87 db speakers, or not enough gain, or perhaps both. If the problem is not enough gain, there are probably solutions that are considerably less expensive than purchasing new speakers.

Regards,
-- Al

P.S. to my previous post: Keep in mind also that the difference between the 120 watt capability of your previous solid state amp and the 40 watt capability of the Mystere is only 4.8 db. And the resulting maximum volumes provided by the two amps may have differed by even less than that, if the speakers were starting to undergo "thermal compression" as the 120 watt amp approached its maximum power capability, and also because tube amps tend to enter their clipping region less abruptly than solid state amps.

All of which adds to my suspicion that the issue might be a gain problem and not a power or speaker sensitivity problem.

Regards,
-- Al

@elevick what Zu did you audition?I found huge difference between their lower price models and the Druid.

Specific to Coincidents, I have always wanted to hear.  They are 1st order crossover design correct?  What model do you prefer?