What makes a speaker sound great at low volume?

"What makes a speaker sound great at low volume?"

The "Loudness" switch on my McIntosh C22 preamp...

I have a pair of high end headphones and a good head amp for late night listening. The high efficiency of a speaker is usually a good indicator that it will sound good at low volumes. but you do need to audition it.As another said, getting USED TO listening at low volumes matters a lot. I agree if you listen pretty loud all the time, hear a low volume sounds bad. Where folks like myself who listen at lower volumes all the time, it sounds great!
And most electrostatic sound wonderful at low volumes. As well as high efficiency speakers.

I use the tone controls on my McIntosh C2500 preamp at low volumes.  Does wonders.

A tube preamp will help.

I am thinking of getting the Luxman 509x for my office and one of the big reasons for it is the Loudness switch. It would help big time when I am working in my office at 3AM.