How important is the efficiency of a speaker to you?

@atmasphere well said as usual

@lonemountain everything in the hifi hobby requires evaluating a set of tradeoffs. What "this" you may be willing to trade off for "that" is a personal decision but make no mistake, we each must make a decision of what we are willing to give up in order to get what we value most (and will miss the least).

For me, I prefer no negative feedback and appreciate the delicacy, dynamics, tone and texture that many find in single ended amplification and the speakers that showcase that. YMMV but to describe "limp noodle" as your definition of a given topology leads me to believe you haven't likely heard it done properly.

Many can find what they are after but being open minded helps.

 That the idea that dynamic range is improved or noise floor is changed due to speaker efficiency alone is simply not true?  

@lonemountain  In a word, No. The physics of how voice coils work is the problem.

While there may be examples that support this idea, there are far too many exceptions to make this speaker efficiency issue a universal need?

There really aren't that many exceptions! ESLs are the only speaker that might not be all that efficient but do not suffer thermal compression because they do not use voice coils.

There are attempts to get around the thermal compression problem with lower efficiency speakers, such as vented pole pieces and the like. The incentive is high because lower efficiency speakers are a lot cheaper to make.

For me, I prefer no negative feedback and appreciate the delicacy, dynamics, tone and texture that many find in single ended amplification and the speakers that showcase that.

@ghasley Many amplifiers have troubles with how their feedback is applied (I can explain what the issues are if you're interested). If you get to hear an amp were its done properly, you might have occasion to rethink this.

@atmasphere wrote:

The issue is that most amps made using feedback, which includes high power solid state amps, is that the output transistors usually limit the design's Gain Bandwidth Product, resulting in a loss of feedback at high frequencies (depending on how much loop gain is asked of the design). The result is distortion rising with frequency, which seems to be more audible than the actual distortion spectra created by the amp. Class D offers a way around this problem.

Dependency and "seems to be" - as a technical observation I don't see how it holds an absolute correlation with regard the sonic outcome of SS amps in each and every case and high efficiency speaker combination, and to which degree? Relevance, magnitude and context (in my case also: active configuration) is obviously very important.

The issue here is that a lot of higher efficiency speakers are designed for amps with a higher output impedance.

Wouldn't the design of high efficiency drivers reflect more than a limited range of amp designs of their day? It borders on an anachronistic view, I find, holding that high eff. speakers of more modern/recent years (going back decades, really) should bring about the most favorable sonic outcome with tube amps predominantly. Myself I would be careful not to link local preferences of high eff. speaker designs combined with tube amps as anything that has a strict relation to or foundation in a technical explanation. Mostly preference is just preference (i.e.: highly subjective), but I'm sure many would jump to the gun, so speak, with a technical reference to validate their perceived findings in this regard.  

Such amps try to make constant power rather than constant voltage; this is not a myth.

My context of debunking that myth was in relation to the compatibility of high efficiency speakers and SS amps, sonically speaking. 

The Power Paradigm is what was around before MacIntosh and EV started promoting higher feedback in the mid 1950s so as to cause their amps to behave as a Voltage source, allowing plug and play. You might want to read this article for more information.

Interesting, and informative article. Offering technical insight it must also come to acknowledge that what is advocated here can as well be counteracted perceptively, if nothing else by the myriad intricacies of a context:

Any audiophile will agree that the most valuable thing they have with respect to their audio system is their own hearing. 

Dependency and "seems to be" - as a technical observation I don't see how it holds an absolute correlation with regard the sonic outcome of SS amps in each and every case and high efficiency speaker combination, and to which degree?

@phusis Rising distortion with frequency can cause an amp to sound harsh and bright. A typical example would be if the distortion begins to rise at 1KHz which is quite common; the 7th harmonic is at the upper end of the Fletcher Munson curve, so due to the extra sensitivity of the ear at this frequency, the fact that the ear uses higher orders to sense sound pressure, and the emphasis added by the rise in distortion, you get brightness and harshness. As you know, harmonics are what the ear uses to distinguish the difference between a trumpet and a clarinet; if harmonics are added with emphasis in this manner it causes instruments to sound harsher and brighter. The degree to which this occurs has nothing to do with the speaker and everything to do with at what frequency the distortion begins to rise (the point where the loop gain exceeds the GBP).

Wouldn't the design of high efficiency drivers reflect more than a limited range of amp designs of their day?

For vintage speakers, no. For speakers made since the Voltage rules were adapted, yes. But you'll find, if you look, that most producers of higher efficiency speakers tend to use tube amps. At any rate the kind of amp used has nothing to do with the phenomena of thermal compression. My speakers were designed for amps of higher output impedance, but owing to level controls for the mids and highs (which are there even on vintage designs to allow the speaker to be adjusted to the Voltage response of the amplifier) they work fine with my class D amps.

Interesting, and informative article. Offering technical insight it must also come to acknowledge that what is advocated here can as well be counteracted perceptively, if nothing else by the myriad intricacies of a context:

What are you trying say here? If we didn't have ears, its unlikely that we would be playing around with audio equipment :)

Amazing how complex and convoluted this discussion is.  I don't think there's a good answer here.

Except, having a Quality tube or solid state amplifier with plenty of power is undisputably a good thing. Yes there are speakers that can run off of 10 W of tube power.  Although this confuses the hell out of me.

Sensitivity of speakers is really confusing to me except that more sensitive speakers can be played with low power tube amplifiers and there may be some value in pursuing this because there are plenty of really good tube amplifiers running off of low wattage this can be a good thing. And we all know tube amplifiers are better than solid-state.

It's also good to buy a dog rather than a cat because the cat could care less about you.