What component is responsible for dynamics ?

Hi Face,
My believe as always been do what works best for you and meets your objectives,Having had much experience and exposure to both approaches, personally the high efficient speaker with lower power amplifier has been much more realistic and satisfying(not really close).

But that`s me, your experiences are different and I can certainly appreciate that. What ever road gets you there, follow it.
Best Regards,

Having tried a few different speakers of different efficiencies in my rig over the last few days, I don't believe speaker efficiency has a direct correlation with perceived dynamics.

The two pairs of monitors I tried are a few dB more efficient than my reference towers and they appeared to lack in dynamics, I believe the lack of LF extension is directly responsible for this, although driver size could also be a factor. The towers are tuned to 20hz, meanwhile the monitors are tuned to 40hz and 55hz. The speakers contained a 10" woofer, 2 6.5" woofers, and a 5.25" woofer respectively.

Face, Whats say your monitors are 4ohm and your floorstanders 8ohm the monitor is 92db 1 watt your floorstander is 89db 1 watt. There will be little difference in volume levels.Also one manufacturer could have estimated specs or rounded up or down etc. Now if your floorstanders are 89db 8 ohm and you compare to a 110db 16 ohm horn think you will find your increased dynamic range.

Comparing a small monitor to larger box floor standing speakers misses the point entirely.
Charls

So as is typical on such posts, the answer is everything and nothing.