More power for better sound at low volumes?

I have noticed better low volume sound as the efficiency of the speakers goes up.

... and i think i have also noticed that low efficiency speakers tend to sound better at higher volumes than high efficiency speakers. I could well be wrong of course. Others here have wider experience than me.

Mapman, I dont think high efficient speakers will always be better at low volume. I do maybe 75% of my listening at lower volume so I am very tuned into this with my upgrades. First thing I ask the dealers to do is turn down the volume and you usually hear the life drain out of the music. Many hours and many speakers lead me to think high efficiency helps low volume sound, but I am certain there will be exceptions.