Higher sensitivity - more dynamic sound?

Phusis

I think your post makes my point.  Efficiency alone is not the sole issue or a spec to chase.  Amp power, purpose and many other factors matter a lot.  In live sound, 127dB SPL is important.  In home audio, its damaging to our hearing. 
The 20W limit was only responding the post of the 25W amp mated to an efficient loudspeaker had better dynamics (earlier in this and other threads).   Good amps with high power are very available.

@lonemountain --

I think your post makes my point. Efficiency alone is not the sole issue or a spec to chase. Amp power, purpose and many other factors matter a lot. In live sound, 127dB SPL is important. In home audio, its damaging to our hearing.

The 127dB info only served to prove that eff. + extension is readily possible. I wouldn’t dream of using the max. potential in my home environment, but headroom is your friend, not least in LF, and thus the max. SPL numbers should make more sense in this context. Operating the amps much below full tilt is also worthwhile headroom, I might add.

The 20W limit was only responding the post of the 25W amp mated to an efficient loudspeaker had better dynamics (earlier in this and other threads). Good amps with high power are very available.

But more wattage in low eff. speakers comes with a price eventually, as per Duke’s post just above.

Amp power, purpose and many other factors matter a lot.

Quality wattage where it matters most, and power quantity (and overall quality) ditto; I use 30W class A from ~600Hz on up, ~2kW from ~85 to 600Hz, and 500W below ~85Hz. The pro class D-based amps used below 600Hz are quality amps and more than sufficient for the respective frequency spans - that's one of the beauties of active config. that such a distribution of amp types is possible. 

Valid points all Duke- my point about dynamic range was "system dynamics" not one system vs another.  The 86dB efficiency speaker on a 250W amp has more total dynamics to cover incoming source material of a wider dynamic content than the 102dB/20w amp system. 

Brad

@charles1dad

Thank you Charles, you summed it up wonderfully!

Janos

@audiokinesis 

Thank you for the post. Very interesting. This is something that was in the back of my head to look at for a while but never took the time. To me it makes all these discussions, not to mention the concept of 4, 5, 6 figure speaker cables rather foolish.

Given the electromechanical nature of the drivers, it could be difficult to measure the electrical resistance of the driver(s) in circuit during operation. Perhaps as an academic exercise you could limit the frequency of the incoming signal to say 50 or 60 Hz, and then use a small DC stimulus to measure the DC resistance. You would be severely response limited, perhaps 100 millisecond rise time. I expect someone has given this a lot of thought and has a better method.

Also interesting about the speaker becoming a different speaker at different driver levels. There was an interesting post on ASR recently where a person was "fixing" a commercial speaker. He did response and impedance measurements at multiple drive levels. There were some significant differences, though less after his changes.

You are convincing me more and more that active is the way to go long term.