dB effeciency vs speaker configuration


I want to know the different caracteristics of speaker. Which one of the following technical data would give better musique, less difficulties to the power amp ? Which would give a better match and sound with stereo tube power amp, and, second with a solid state power amp ? Speaker with air vent, or sealed speaker? Speaker with 4 ohm or 8 ohm ? Speaker with 87 dB or 95 dB effeciency ?
audiosens
I won't claim to be an expert, but I would say that if you can find the display of impedance and phase across the audio spectrum of any given speaker, you should be able to determine whether or not an amp will be able power it. Though, you need to be able to understand what it is displaying.
Just my 2 cents until brighter minds chime in...
I will defer to Almarg, and Atmasphere, who are probably the best qualified to answer here on Audiogon.
Well technically its sensitivity but the difference is hard to explain so efficiency will do. Which one sounds better is impossible to say. Pretty obviously there are great examples, as well as examples that suck, of every design. For every guy who swears by electrostatics there's one in love with horns, for every port lover there's a sealed supporter. 

In terms of amps though its still hard to say its at least a little more clear. Speakers with low sensitivity are gonna be a lot harder to find an amp to make them sound good. Tube or SS. 

Problem being, its hard enough to make even just one watt sound good. Then if you want louder, which you do, well then both power and volume (dB) are log scale. What that means is to play just 3dB louder, which does not sound like much, requires twice the power. 10 dB requires ten times the power. 

So a speaker with only 86 dB sensitivity, that on paper looks not hugely different than 92dB or even 96dB, in reality is gonna need four to ten times the power. 

In practice you go with what sounds good. Regardless of how its made. But no matter how much you might fall in love with one you will be well advised to stare it down real good if its sensitivity is below 90. People do, it can be done, but the 87 you mentioned will need nearly ten times the power of your 95 example. And good luck with that. Because you will need it.
 If you want to use tubes, generally speaking, higher efficiency and higher impedance are desirable. 
Every 3 dB of improved efficiency cuts the power required by half.

Most tube amps can drive 4 Ohms, but they are sensitive to variations in the impedance. Examining the impedance curve can help find things to watch out for.


See the black line in the very first chart for a typical example of how a spaeker's complicated impedance can interact with a high output impedance amplifier (typically tubes):


https://www.stereophile.com/content/balanced-audio-technology-vk-56se-power-amplifier-measurements

Best,
E
I tend to like low powered amps, tube or solid state class A.... with higher efficiency speakers.    I've had some great sounding lower efficiency speakers, 83 to 86 dB/w  but they all ran out of steam quickly and needed a lot of power to shine.    My current setup is a pair of Klipsch Heresy III with a pair of 40 w Quicksilver monos and they sound as close to live music as I've ever had at home.