Efficient speakers v. less efficient speakers

You cannot compare efficiency alone without considering speaker/cone size and overall design...it is always a compromise.

The question:

If driven with the appropriate amplifier(s), meaning a higher powered amplifier for a less efficient speaker and a lower powered amplifier for a more efficent speaker, are there any difference?

The speaker design is generally what makes the difference.

An inefficient bookshelf speaker with a big amplifier can be comparable to a full size efficient speaker with a small amplifier when played at acceptable sound levels for both the bookshelf speaker and small amp.

A bigger speaker can ultimately go louder with less distortion particularly when pared with a big amplifier.

On the other hand,

An efficient bookshelf speaker, is rarely comparable to a full size efficient speaker.(Bookshelf being roughly up to 6" woofers, and full size being 12" or larger woofers)

In very general terms:

1) big speakers can be efficient, and play loudest with lowest distortion
2) small speakers tend to be inefficient if they have low distortion.
3) efficient small speakers tend to have the highest distortion even if they can play quite loud with a modest amplifier.

I`m GLAD to hear that! I have Infinity SM-152`s and
2 pairs of SM-155`s. They`re rated at
sensitivity 102db at 1 watt.
My Pioneer Elite C-91 pre-amp volume, sits at
9 o`clock MOST of the time,
that`s about .7-.9 watts per channel.
They DO sound loud.

Sorry I wasn't as clear. I intended my comments to apply to your stated comparison of efficient speaker plus low powered amp versus inefficient speaker plus high powered amp. My experience is that the inefficient speaker plus the high power amp will sound somewhat compressed and lack air and detail. As your original question implies, there is more going on than simple matching of efficiency with power. So, my answer is yes, there is a difference.

Rlew - I intended my reply to be a direct answer to your question. There will be a difference and it is mostly due to the speaker designs being inherently different. The amplifier power level is largely irrelevant assuming you are comparing same sound pressure levels - something your question implies.

Isellstuff - The volume knob position has nothing to do with power output whatsoever. If you used a power meter to calibrate it, ok, but if not, you have no way of telling what the actual power output is in absolute terms. Arthur

Short answer: no. You cannot generalize that higher sensitivity speakers paired with a low powered amplifier is equivalent to a high powered amp and low sensitivity speakers at a given sound pressure level. It depends on the quality of the amps and speakers. If you take an X brand amplifier line of two different wpc ratings and match them with speakers with different sensitivities and listen at the same SPL, then you will be essentially hearing the differences of the speakers - assuming that the amplifiers of the same line are very similar sounding and everything else equal. And overall speaker performance goes beyond, and not solely dependent on, the sensitivity rating.

High sens speakers are not necessarily better - if they were, then everyone would own them. Everything in audio is a trade-off, and high sens speakers are no exception. They require, among other things, low mass drivers and high magnetic flux which introduce distortions that rigid high mass drivers in low sens speakers do not have. Also, by their very design, they may have to result to horn loading to reach down to the lower midrange to bass frequencies. So what is actually "louder" or more "dynamic" may be mostly the upper frequency range.

So, for a given cost, it's basically either louder with a relatively limited frequency response (especially in the low end) or softer with a wider frequency reponse.