How important is the efficiency of a speaker to you?

75 Watts is fine for 86dB speakers. (Dynaudio) Just my experience

If you want/like 8 ohm 86 dB sensitivity speakers you will most likely have to go with a high watt output solid state amp (>150 watts). 

It takes 150 wpc plus (ss) to drive a speaker rated at 86 db?

You can also make a more efficient speaker by "tightening up the tolerances" (i.e., tighter fitting voice coil/gap) and increasing the number of windings within the same area (e.g., using flat-wound wire), without causing other problems.

BTW, a lighter cone will also allow the driver to play to a higher frequency without break-up.

My "Merman" speakers are extremely efficient, and sensitive, without horns, and can easily do "live concert levels" and I wouldn’t have it any other way.

Remember that the volume control is nothing more than a "focus knob" and sometimes you really need that volume to bring the cut into focus.

Also, I feel that an "immersive experience" takes realistic volumes to achieve.  You can't immerse yourself in a tub of water if it only covers your toes. 

I think many of the values discussed here and elsewhere assigned to high efficiency speakers are not accurate. First the entire discussion of what is delivering the improved efficiency is not differentiated- is it drivers or how the driver is used that gets you better efficiency? These two ideas.make a huge difference in performance but are distinctly different methods of achieving improved efficiency with their own costs, benefits and penalties..

Example 1: a lower efficient driver can be made more efficient by placing it on a horn, which complete changes other characteristics/parameters of performance and behavior. An acoustic suspension system or a horn system are very different from each other in many ways having a direct impact on performance.

Example 2: You can build a more efficient driver by lowering the mass of its moving parts. Lowering this mass can cause multiple things to happen, typically increasing ring modes and distortion. Here efficency makes the driver sound worse. Another outcome of lowered mass is poorer low frequency performance.

Example 3 Higher efficiency drivers do not always offer lower power compression. If you use titanium instead of aluminum for your former, the thermal resistance is far higher with titanum than aluminum, so heat can’t escape the lower mass system increasing thermal power compression. Higher efficiency increases thermal power compression in this case. DO you know what your VC former material in the speaker system you buy actually is? Thermal power compression is affected by a long list of factors that are far too detailed and complex to discuss here or ina spec sheet: issues such as VC impendance, VC material, front plate/pole piece proximity to coil, airflow and venting of the magnet system. Looking at a efficiency measurement and assessing quality is like looking at frequency response and assessing sound quality- it really isn’t an indicator of performance in a way that is simple or easy to [universally] understand.

I know poeple really want there to be a simple way of looking at things but this is some deep science. A speaker involves practicaly all the sciences and there is no way to simplfiy it and express that in a spec- unless you are willing to bullshit or tell a helluva convincing marketing story. Most do exactly that, but its a diservice to the thinking person’s aims in a playback system.

If you love the idea of a flea watt amp, you are sorta stuck with high efficiency loudspeakers to have any hope of dynamic range. If you are more open minded and are wiling to look at moderate efficiency speakers in the mid 80s, using the wide array of excellent high power amplifiers available, or active speaker configurations, you can have your low distortion, wide dynamic range AND better bass AND wider dispersion, etc, etc. But you cannot have all that AND super high efficiency.

I think we are back to listening to a speaker with a proposed amplifer and assessing if this combination works for you and addresses the things you care about.

Brad

.

Ok I have Polk lsim707 ,88 db and thery are driven with a Caryin XL 55 tube amp light 20 wpc and they sound great....there in a very large room with cathedral ceilings....i was,told owe you can't drive them with that tube amp....you need 300 wpc.....well they were wrong ,totally. I have used these hook up for 2 years.....no problems at all....

@dhite71

+1

There has been this old adage of tube watts being more powerful than solid state watts. For most of the last fifty years I used mammoth high powered solid state amps. Then about five years ago switched to Audio Research Reference amps 160m monoblocks and 160s. I run the 160s in triode mode… so only 70wpc and they are ferociously relaxed and powerful, absolutely no lack of muscle… but they don’t flaunt it… it is just there, rock solid at any volume.

I also have a friend with a pair of Wilson Puppies and an Audio Research VT80. They drive the Wilson’s to incredible loudness without any sign of running out of power or dynamics, rock solid. I really cranked them last weekend.

While I haven’t recently tried to put 70wpc tube power up against solid state but I am pretty sure it will stand up against two or more times the SS watts. So, I had figured the old adage of the difference between tune and SS was really subtle. It isn’t and still seems to be there..

Interesting discussions on efficient speakers...  I have run through the gambit of lower efficiency 87db-89db speakers and efficient 94db and very efficient 103db - 106db.  And I've also gone through the same regarding the amps I believed needed to drive them.  After my experiences over the past 20+ years, I moved toward the higher efficiency types (94db - 106db) with low-wattage (flea-watt) class-A single-ended both tube and solid-state amplifiers.  As I moved from lower efficient to higher efficient speakers keeping my higher-powered amps in play, I could tell the difference in micro-detail.  Going then from the higher-powered amps to the flea-watt amps, there was a slight but noticeable improvement in micro-detail, with no loss of dynamics or bass response at my normal listening levels.  Those speakers by the way had impedances between 6-ohms and 8-ohms nominal and all had multiple drives/crossovers.  Presently, I'm using a single-driver speaker with of course no crossover, that is 106db efficient with a 12.9-ohm (resistive) impedance.  Every one of my flea-watt amplifiers can drive these speakers to uncomfortable listening levels with absolutely no loss of any dynamics.  However, I would expect that at a 106-db efficiency, and at the rather high 12.9-ohm resistance.  Even my 94-db speakers were driven with the same flea-watt amps with no dynamic compression at comfortable listening levels.  I have not heard a variety of lower efficiency/impedance speakers, however in every case with the speakers I've had, the more efficient the speaker, the greater micro-detail I've heard.  The only other lower efficiency speakers I've heard equivalent or better micro-dynamics, especially in the upper mid/tweeter frequencies are planar speakers.  Perhaps that has more to do with the lower moving-mass of the planar electrostatics than the efficiency.  Finally, one of the tests for me was the low, no-signal noise from the electronics through the speakers.  If you can hear that slight noise with very efficient speakers versus lower efficient speakers, what micro-detail would you then be missing in the music with those lower-efficient speakers ?  Your individual experiences may vary.  This is just what I've seen/heard over the years...  

The speakers I was referring to were not Wilson's. Nonetheless, it is interesting what you posted about Alexia 1's. They are known to be extremely difficult to drive. Is it possible that the ARC Ref 75SE has a more capable transformer, and as such can drive the Alexia's? 

This sounds like Wilson Audio, which I have.  Do not assume everything you read.  I recently auditioned a pair of Alexia 1 that are supposed to require lots of SS power.  The sounded better and more musical at the same output with an Audio Research 75SE than they did with a McIntosh 450wpc SS amp.  

antigruge2, that is very interesting recommendation about trying a set amp. This has been recommended before and I look forward into to getting one to try in the near future.

@phd 

At 102db efficiency may I suggest you try SETs rather than push pulls? You might be in for a big surprise. A classic 300b amp will amply drive those speakers unless they have a weird impedance pattern

I own very large efficient speakers (102db) and although they can easily be powered by a tube push-pull amp tube amp (10 watts per channel) to reasonable and higher levels they still sound really good with the bigger more powerful ss amps. The point is if you buy efficient speakers you are opening up all doors to amps of different power output.

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. 

Sensitivity vs. Efficiency see below page one paragraph C:

Mike

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

There is a difference between sensitivity and efficiency.

Herman = +150

Toddalin = -165

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.

If you look into this a bit further you will discover that these other waves are combinations of sine waves, and there are no musical signals which have an instantaneous rise time. If you put any musical signal through a spectrum analyzer you will see it broken down into these various frequencies.

https://mathworld.wolfram.com/FourierSeries.html

As the article you dismiss states, once the slew rate of the amplifier is high enough that it can amplify the highest required frequencies without distorting them (it is not slew rate limited) then a higher slew rate does not matter.

I’ll leave it to you to dig in and educate yourself about this, since instead of trying to understand slew rate, it appears you are only interested in proving you were right despite the fact what you initially stated is undeniably incorrect.

I’m done with it. Good luck in your journey.

The whole article flawed because it is based solely on the use of sine waves.  I don't know about you, but I listen to more than sine waves (and possibly flutes).

But square waves, sawtooth waves, and complex waves have "verticle" (i.e., instantaneous) rise times and this is where slew rate would come into play.

https://www.audioholics.com/audio-amplifier/amplifier-slew-rate

"I’m sorry, but your understanding of slew rate and how it applies to how an amp operates is simply incorrect. Slew rate describes how fast an amplifier is capable of changing, not how fast it is changing. It describes the maximum rate of change, not how how fast it is changing for a given input."

I understand this.

So then, you are saying that slew rate has NO IMPACT on how a speaker sounds??? So then why do the "better amps" try to achieve higher slew rates, resulting in "squarer" square waves?  In fact, by your terms, why bother to even measure it?

"an amp operating withing it’s specifications that is producing 100 W RMS at a given frequency will reach peak power in the same amount of time as a 1 W RMS amp will."

 

You missed the point. I said ALL OTHER THINGS BEING EQUAL. So the same amp, be it 1 watt or 100 watts, is used with both speakers.

Obviously a 100 watt amp will produce 1 watt (0.278 times the voltage) quicker than it will produce the full 100 watts.

I’m sorry, but your understanding of slew rate and how it applies to how an amp operates is simply incorrect. Slew rate describes how fast an amplifier is capable of changing, not how fast it is changing. It describes the maximum rate of change, not how how fast it is changing for a given input

The point is, slew rate has absolutely nothing to do with efficiency or how dynamic a speaker is or anything being discussed here. Your concept of slew rate is wrong. Sorry if you don’t get that.

@herman Would that be in Denver or NYC?

I have absolutely no idea what you are talking about

"an amp operating withing it’s specifications that is producing 100 W RMS at a given frequency will reach peak power in the same amount of time as a 1 W RMS amp will."

You missed the point. I said ALL OTHER THINGS BEING EQUAL. So the same amp, be it 1 watt or 100 watts, is used with both speakers.

Obviously a 100 watt amp will produce 1 watt (0.278 times the voltage) quicker than it will produce the full 100 watts.

Even a perfect square wave has a "rise time" and obviously it passes through 1 watt on the way to 100 watts.

I have been using for 39-46 years the following:

- Altec Lansing 604Cs: 101db efficiency, 26 ohms. 
- NYAL Julius Futterman OTL3 monoblocs, converted to triode, about 135 watts each. 
 

theaudioatticvinylsundays.com/about

@herman Would that be in Denver or NYC?

Efficiency is not the issue, unless you have a silly pea watt amp. What you like to listen to is the issue and speakers, being the most difficult of all components, are always a compromise. I'll only listen to Line source dipoles. They are usually not very efficient. 

@danager 

Thanks for posting the link. 

The amplifier takes time to make this power (i.e., slew rate). So the amp "slews" 3.16 times faster to reach the same volume level resulting in increased dynamics for the high efficiency speaker.

that's not how it works, that is not how slew rate factors into how an amplifier works. Slew rate is directly related to bandwidth, not how quickly it reaches peak power operating within it's specified bandwidth. 

 an amp operating withing it's specifications that is  producing  100 W RMS at a given frequency will reach peak power in  the same amount of time as a 1 W RMS amp will.

Example.... at 1000 Hz the period is .001 seconds. So starting at zero crossing  it reaches a peak  .00025 sec later , crosses zero in the opposite direction at .0005 sec, the opposite peak at .00075 sec, and back to zero at .001... no matter how much power it is producing..  If it didn't it would be distorting the signal. 

Not particularly important to me.

Not very important. 

The best speakers I have ever heard, and the best I have ever owned (not in the same set, I could not afford the best I've heard), have all not been very efficient.

My old Koss Model 1a full range electrostatic speakers were 87db. But the clarity, detail, attack/decay, soundstage and image they produced are better than pretty much any high efficiency speaker I've heard. 

 I can think of a few exceptions, like the Acapella Audio Arts Hyperion, with their plasma tweeter, and their built in amps for the woofer section. 

@ronboco 

As far at cost to achieve SET sound with power I have no idea.  If you're are really interested you should reach out to somebody like Pat Hickman at Whammerdyne.  He builds both "flea watt" and hi power hybrid amps and I'm sure he could explain both the benefits and drawbacks of the different levels of power.

High sensitivity speakers w/ true bass extension necessitates large volume cabinets which can mean more $ & potential room / aesthetic placement challenges. That said, as John Atkinson often points out, high sensitivity drivers have substantially less distortion at higher output levels because of the much lower current flowing through their voice coils which generates much less heat & are “ working” much less hard. That said, some may not like the sound of the driver type used to create that high sensitivity ( horns, AMT’s etc). Every method has trade offs.

My own personal preference that to me sounds closest to live music is high sensitivity horns w/ tube amps but not “ flea powered” if you like to listen up loudly in a big room. Very difficult for just about any  lower sensitivity speaker at any price w/ even w/ heroic amplification to match the speed & instant dynamics of a quality horn loaded one. 
 

Volti Audio Rivals do it for me….

I think a very reasonable argument can be made for low-power amps, along the lines of “the less you mess with the signal, the better.” So assuming you select a well-designed amp, you simply find a speaker that pairs well with it. I have a couple of Pass diy amps with 15 to 25 watts. I’ll call that low power in today’s market. So to go with the 15-watt amp (at 8 ohms) I built speakers with 95db efficiency. Nice sound, really sweet midrange in a 20x20 family room. The 25-watt amp is a little more flexible. It makes 40 watts at 4 ohms. And I like Magnepans, but they’re 86 db and 4 ohms. I tried it and liked it. Volume probably tops out in the low 90s db range in the large room they’re in, but it’s a living room, not my music room, so fine by me. I’ll add that among the high efficiency speakers I have hear at stores and with my local audio group, they have a dynamism I find appealing, really lively. But I value timbre above all, and that usually leads me to Maggies.

Good to see how many people are getting on the high sensitivity train.  Why do I care?  More users means more choices by manufacturers.  The economics point big manufacturers to the expensive insensitive speakers.  

Some great posts here.

And some denying.

Jerry

@danager 

What price  level and brands would you say have overcome the obstacles to achieve top level performance? 

@ortodox 

02-29-2024 at 11:56am 

I went from 87 db speakers to 94 db speakers. Much better sound at low volume and less power needed.

****

I had a similar experience with going from 85 dB sensitivity (84-86 depending on whose numbers one is to believe) Ohm-Walsh 4 speakers to 92-94 dB Klipsch Heresy IV. 

I WAS using an updated (by me) ADCOM GFA-545-II to drive the Ohms (GREAT for RAMMSTEIN!), got into a class AB 6CA7 tube amp - Willsenton R8, totally modified/updated by me - then got the Klipsch speakers and a Tektron TK2 2A3/50I-S amp running 300b tubes.

Just before selling the Ohms, I hooked them up to the class A Tektron and they BARELY sounded like anything but hollow, without presence, a very narrow soundstage, vague, muddy.

I connected the ADCOM amp for the buyer and he was sold on them within seconds of hearing “In Your Eyes.”

I’m using 2A3 tubes now and enjoying 50-60’s Jazz more than ever.

Sensitivity, power driving the right speakers, makes a YUGE difference.

addendum:

Funny, I can remember a conversation I had with the father of a girl I was dating back around 1974 who said “you only need about 2 watts to listen to music” when the stereo we were playing was something like 50 WPC and after 50 years, I’ve come full-circle to pretty much the same conclusion.

YMMV. 

@deep_333 

Here is a white paper written by Steve Deckert that explains it much better than I ever could.

https://www.decware.com/paper43.htm

Flea watt amplifiers are class A with minimal circuitry and no negative feedback as opposed to a high powered amplifier that relies on a much more complex circuitry and many more components.  As components are added there is a gain in power but it comes at a cost.  Top of line amplification can minimize those loses with higher quality components and advanced designs but they then become very very expensive and totally unnecessary with a well designed high efficiency speaker.

I'm running corner horns with two watts and can reach 85 to 87db in in a very large space without a sound deficit that's apparent to me.  I'm not able (or want) to play at 110db but I still have bass I can feel in my chest and a detailed sound stage that's simply glorious.

@deep_333 

My comment relates to the high wattage, complex crossover+DSP school of engineering. I have yet to hear a system built that way that offers true timbre and time allignment of its various components. Flea watt amps are not a must but many valve enthusiasts swear by 2A3s.

Flea watt amps are anything but dumb. Low watt amps and high efficiency speakers are about transient speed.

Huh?? @danager , what transient speed did you obtain with a flea watt amp paired with the high efficiency speaker that a meatheaded amp couldn’t do (with the same speaker)? Please elaborate. I have nothing against high efficiency speakers. I do have a problem with this flea watt miracle (supposedly). Essentially, they tend to gimp such speakers.

That’s why flea amps with high efficiency speakers have such a strong following among true audiophiles

@antigrunge2 ....Again, no problem with high efficiency speakers. But, ugh, what the hell benefit did you get by pairing it with a flea watt amp?? A "true audiophile" like you knows of some mystery that an "untrue audiophile" like me doesn’t get perhaps?

.

@daveyf wrote:

How important is the efficiency of a speaker to you?

In effect: a lot. Comparing speakers of different efficiencies isn't an apples to apples scenario. With either "camp" there are implications with regard to the nature of directivity (and -uniformity), driver and enclosure size, driver type/segment and other, which in turn has sonic consequences. My eventually veering towards the high efficiency segment of (large) speakers wasn't due to some blind rationale of attaining high efficiency (and SPL) in itself, but rather what those speakers offer in vital parameters of sound reproduction that separates them from the low efficiency segment of speakers here, also with regard to the interaction with acoustics. 

With passively configured, low efficiency speakers it was very much about finding that particular speaker which had the desired characteristics in a given listening space. Not an easy task. With DSP-based and larger, high eff. speakers that are outboard actively configured it's more about getting the basic physics and design execution in place as a framework to go by, call them macro parameters, and then slowly work your way in from that outset to get to where it all gels. 

The worst outset dynamically are small, passively configured, low efficiency, low impedance and load-heavy speakers, although it's the bigger multiway iterations that'll more readily get the amp(s) to their knees. Even served a ton of watts such speakers never escape the fact they're the sonic equivalent of a liquid-saturated sponge that never truly lifts off and comes to life.

Getting rid of a complex passive crossover is a good start, and then higher efficiency will be a further improvement - certainly dynamically. Amp-wise I'm not really the SET-guy (although they can sound great through very high eff. horn speakers), but I like class A/B studio designs which in my case are high powered (~600W/8 ohm per stereo amp, three of them) and of the same brand and series. They're essentially similar top to bottom, incl. the subs, and it pays off sonically. To those squinting at the high power rating here, remember it comes down to how it sounds..

What many seem to forget is that bi-amping actively will have each amp delivered its limited frequency span to feed its respective driver segment (as opposed to passively where they receive the full signal). So, the amp unloading power into the subs won't affect the other amps at all, the HF-amp is relieved of LF, etc. - with all that implies.

No power draining, complex passive crossovers; high efficiency, large and sufficiently tall speakers (i.e.: 97 (plus corner load) to 111dB sensitivity); plenty of power from independently configured amps, not too heavily damped acoustics - to me this is all about efficiency, less energy store-up and achieving proper headroom. Not as parameters standing on their own, but an essential outset to build on. 

A high efficiency speaker takes less watts to drive to the same volume level as a lower efficiency speaker.

ALL OTHER THINGS BEING EQUAL... If a speaker is 10 dB louder than the other, it takes 1/10th the power to drive to the same volume level.

The amplifier takes time to make this power (i.e., slew rate). So the amp "slews" 3.16 times faster to reach the same volume level resulting in increased dynamics for the high efficiency speaker.

@daveyf Wrote:

 When I mentioned this to the person doing the demo, i was basically belittled, as he felt that the efficiency of a speaker is pretty much irrelevant 

The importance of speaker efficiency: The article below is from 1962 and is as relevant today as it was then. In my opinion, a high powered amplifier that can drive lower impedances will never be a proxy for a speaker's lack of true efficiency. 

Mike

https://www.lansingheritage.org/html/jbl/reference/technical/efficiency.htm

I went from 87 db speakers to 94 db speakers. Much better sound at low volume and less power needed.

I prefer speakers with a sensitivity range between 86-88 dB; I dislike those with a sensitivity higher than 88 dB because I want to avoid any hiss from the speakers. Contrary to the belief that high-sensitivity speakers perform better in low-level listening, the key lies in how you adjust the equalization to achieve a proper ELC.

Another misconception is that people believe high-sensitivity speakers can be driven by lower-wattage amplification and produce equally good, if not better, sound quality. There are a couple of reviews demonstrating that the Klipsch Cornwall IV (102 dB) can be driven with a higher-power amplifier to achieve better sound quality with more control throughout the frequency range than lower-power counterparts.

My thinking is that efficiency is a product of both reactance (impedance and phase angle) and sensitivity. The reactance relates most toward 'easy to drive' while sensitivity relates more toward size of room to be pressurized. 

Since the Fritz speaker has been mentioned, I will add that Fritz speakers are easy to drive having a benign reactivity. A sensitivity around 88-90dB allows them to be played in smaller rooms with low wattage amps. As room size increases power requirement also increases however I can't imagine anyone needing more than 100wpc to drive them to their maximun output. If one is playing them that loud their room size/listening level likely is better suited toward a larger speaker.

Efficient also means the drivers don't have to work as hard to make music...It's been scientifically proven that efficient drivers are happier. Also factually true is a 500 watt or so amp into efficient speakers might be using 1% of its mojo. And yes, the correct term here is "mojo."

More Efficient just means louder. Alone it has little to do with what amps will drive the speakers well ie produce the intended sound completely. That has more to do with how difficult a load which is more about impedance, not efficiency.

So really all more efficient means is a flea powered tube amp can make them go louder before clipping sets in. It does not mean one is getting all they can out of the speakers regardless of amp. That’s not to say the results will necessarily sound bad, just not optimal, and different with different amps, not the same

Take Fritz speakers as an example. If you check out the website you find these are designed to be an easy load for any amp but are not high efficiency. They will sound more similarly good off most any amp and still achieve decent SPL with most any amp, so they are an excellent choice for someone who wants to get best end results using most any amp. The site also shows how the Fritz speakers compare In this regard to other popular speakers. 

@ghdprentice   I agree with this. Not only do you restrict yourself to a subset of speakers, but in the worst case examples, you also restrict yourself to a subset of amps. Like many of us, i know of a few a'philes who bought their dream speaker, only to find that the amp(s) required were a deal breaker, not only from a budget perspective, but also in many cases, from a placement/heat/aesthetics/weight perspective as well.

My point of view is that it is a challenge to find speakers that perfectly match your specific sound quality values. It gets much harder by restricting yourself to a subset of speakers. 

generally not important, unless it's extreme...

I have main-system speakers of 89bd/4ohms, 91db/4ohms, and 102db/8ohms. They match up with main amps of 100w Class A SS, 65w PP tube Class A, 8w SET, respectively. Each time I swap in a new combo, it’s my favorite. Many roads to Dublin.