How important is the efficiency of a speaker to you?

But to "composite" a square wave from sine waves would take sine waves way up into the ultrasonics and where would that put the slew factor???

A Hammond uses exactly the technique to which you allude. But it never achieves anywhere near a true square wave.

Actually, one could make the argument that a sine wave is just a bunch of square waves with short duty factors and their amplitudes arranged in a "wave" pattern. But again, how many would it take to achieve the true sine pattern?

No musical signals with an instantaneous rise time?

If you play a square wave and the amplifier produces 17v/ms and the speaker needs 17 volts to reach the desired volume, it can occur in no less than 1 ms.

If the other speaker is 10 dB more efficient it only needs 5.4 volts to play the same volume so it can occur in no less than 0.32ms.  That's the math.  Whether the speakers can actually keep up is another matter/discussion.

Regarding being right... it seems that you read one thing and think it applies to all cases..., and obviously it, and therefore you, must be right. Show us something where slew factor is discussed in relation to other wave forms as they actually exist. You are only presenting one side of the argument.

Herman = +150

Toddalin = -165

There is a difference between sensitivity and efficiency.

Sensitivity vs. Efficiency see below page one paragraph C:

Mike

https://www.lansingheritage.org/html/jbl/reference/notes/tech1-3a.htm

Is not the concern the perception of sound that is being produced the factor that determines how one chooses a Speaker.

Speaker Design will require a certain downstream electronic support to enable them to function something like the design intended.

As the Speaker in use in the home or new listening space, the speaker as a result, is no longer in the room or allocated space used to produce the design.

When the speaker is in use in the home it is already compromised, as it is no longer functioning as per the design did when in the space used during its creation.

What matters next is how the Speaker delivers sound, is it Voluminous or Confined, is the Sound presented with Speed or laid back as a delivery, is colouration perceived as being present and being an influence on how the quality of sound is perceived.

How a Speaker is driven does not have too much influence on these attractive traits, it is the downstream devices that manage the transfer of the signal to the final manager of the signal being the Xover, prior to electrical signal being converted into mechanical energy and hence sound being produced.

If the signal is deficient, the Speaker can not add the data that is missing.

Speakers are most liked when the Speaker is capable to produce the perception of the following as the extracted data from the recording:

Dynamics - Micro Details - Attack - Tone - Timbre - Envelope and Coherence - are what really wins ones full admiration and attraction when experienced being delivered.

Such a perception of these traits presence will be much more aligned with the quality of the generated and transferred signal from source to Xover, and not the means used to create the required AC Current necessary to drive the speaker.