Although one has to define what it means "to sound good at low volume", but in term of speaker design, if you want you make your speakers sound "good" at low volume, you want a slight lift at the mid range and upper mid range frequencies, but then it would compromise high level volume listening.
One the other hands, if a speaker frequency response is relatively flat, it needs a bit of volume level for it to come alive.
One the other hands, if a speaker frequency response is relatively flat, it needs a bit of volume level for it to come alive.