Why are high efficiency speakers preferred for low volume listening?


I am sure that this is a very basic principle, but as I peruse the speaker section I frequently see high efficiency speakers suggested for those who listen at "low levels." And is this another area that actually is "how easy the speaker is to drive (as related to its nominal impedance)" that is more important than the actual sensitivity number?

And for an example of what I am asking with that last sentence, I seem to remember when I was window shopping for speakers, seeing some Harbeth speakers at TMR with a sensitivity rated below 87 (I think they were rated at 86 or 85) but being referred to as "an easy load to drive." So would that mean that the Harbeth speakers would be good for low volume listening?

immatthewj

My Kef blades needed volume to sound dynamic with my 300 wpc hegel so imagine my surprise when I tried the mc611’s and with the power meters bouncing around .6 of a single watt I was listening to tuneful bass and multiple layers of tones I previously had to really turn up to get? I almost never exceed 6 watts peak output yet the sound is completely unrestricted. Listening to delta cream, the black keys while typing this and am stunned by the dynamics at around 1-3 watts. Can anyone explain 

Duke pointed out good reasons. But one I have not seen is controlled directivity many mid range horn designs react less with room boundaries. This can increase detail at low levels. Also many low eff designs have complicated networks these require more amplifier power and this can cause a speaker to only sound good at louder levels.

@steve59 The meters on an amplifier are not going to accurately measure the peak power you are using, in fact not even close.

I hear you, and thats what I’ve thought from the beginning but the consistency has been giving me doubt.