Amps that bring liveliness to low efficiency speakers?

McCormack and PSE made excellent amps that might fit the bill.

Try an Aesthetix Atlas. Powerhouse with great sound, drive, and bass grip

Bryston

Proceed HPA2....I like mine. Drives Aerial Acoustic 7B tower speakers very nicely in my very limited experience.

Perreaux 2150B. 200wpc/8ohms, 400wpc/4ohms. Clipping at 300+ and 500+ watts respectively! Three now for sale on EBAY - $600, $800 and $1290. I bought one to use with my restored DQ-10's - a speaker that really benefits from a powerful amp!

It might help if you tell us what speakers and gear that you have.  The lack of liveliness could be due to a very warm sounding preamp/source and/or speakers rather than being inefficient.  But more watts on an inefficient speaker is always good.  If your have a very warm system, Bryston is probably just about the fastest responding amp I know of.

Pure Class A!
I read a review years ago on the Dynaudio Special 25’s..The most musical system was a Cayin Class A SS amp and the reviewer stated that because Class A is always "on" it allows saturation of the crossover and faster response time giving them much better low level response...

Look at Pass 350.8 or 250.8 very dynamic with  great  staging  and bass also a great co.

What is your budget ?and what kind of speakers ?

Cayin h80a amp. 80wpc of pure class a. 
Dual mono design. Can be had used for 1500 or so. Drives my mc-rl21s, which are 4 ohm, to sonic heaven. 

Allow me to clear up all this intrigue.

KLIPSCHORNS & Marantz 2252 or 2270


You'll thank me  :>)

Seconds on Pass amps.

Any of the Linear Tube Audio offerings. My favorite being the 20 watt UltraLinear.

If you are looking for liveliness and dynamics then you should try out the Gryphon Diablo 300.

REGA Osiris integrated amp

Lots of good options mentioned already.
Plinius Integrated or a Plinius amp.

Absolutely the Pass Labs 350.8 or 250.8. They are very fast and very powerful.

Look for a Crown Macro Reference, Esoteric version, If you are looking for " live ", beats all the others. Enjoy ! MrD.

^  I have one of those - in need of repair :-)

Good Listening

Peter

Bryston 14b3. Mine clipped at 680 watts on the bench.

I have owned several class A and A/B amplifiers made by some of the best (Pass, ATC, Forte, Coda, Levinson, Meridian, Linn, Krell, etc) and the class D Digital Amplifier Company amps bested them all! No grain or grit with “meat on the bones” tone and detail in spades! 

You stated no class D but damn DAC amps are that good!

Contact Tommy at DAC and he will help you find the best amp to fit your needs. 30 day return policy! 

https://www.cherryamp.com/