Basic question about sensitivity

on highly sensitive speakers, you can blow on your glowing tubes and hear wind from speakers, but on the good side all you need is quarter watt. 

On my experience, the size of the room & the volume you like to listen at have a huge impact on how much power you need for your speakers as well as their sensitivity. If you think about, the word “volume” applies both to the amount of db a speaker outputs as well as the cubic footage of the room. 
 

As Audioman58 pointed out, musical peaks,  both in the bass & lower midrange, can can easily demand 5- 10 times instantaneous peak power. I listen regularly in a large room ( over 6000 cubic feet) at volumes in the lower yo mid 90’s db’s & my 98 db sensitive Volti Rivals are barely using a few watts as indicated on the watt meter on my amp but when a loud peak comes, that can jump to 20 - 30 watts for a split second. 
 

Btw, I’m sure many of you folks are not horn loaded speaker fans but if you like your system to easily boogey on any kind of music & sound rich, detailed & not hard without really breaking a sweat, check out Volti’s! As Greg Roberts says - “have fun!”. 

OP,

Thank you for the question, I have had the same thoughts. I have four speakers:

(1) Thiel CS 2.3 - 87 db at 4 ohms

(2) Old school 1980s Infinity Reference Kappa 7s - 88 db at 4 or 6 ohms (don't understand the two values there)

(3) Buchardt Audio S400 MKIIs - 87 db at 4 ohms

(4) Clayton Shaw Caladans (on order) - 93 db at 4 ohms

I've never really understood the relationship between sensitivity and impedance, and how that translates into "easy or difficult to drive". Furthermore, how does that translate into the proper speaker cable: length, type of material, cable gauge, etc. It's never been an issue for me (that I've noticed), as I never listen to music at LOUD volumes....though I'm sure there is more that I should be paying attention to.

Also, why have I been drawn to the sound (except for the Caladans which I have never listened to in person) of 4 ohm speakers? Is it chance, or something more to it than that? It would seem on the surface, that I've ended up with speakers that are not the easiest to drive

It simply means that at one watt of power a speaker will produce the given amount of decibels. A flea watt amp will drive those Harbeth’s just fine, but it may not get loud enough to work in larger rooms.

@immatthewj,

Speaker sensitivity and efficiency are related, but not the same. See article below page one sec C:

Mike

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