A large horn system can be one of the best choices for low-level listening. One of the reasons that conventional designs require compensation isn't so much the fault of the human ear but of the modern loudspeaker. Horns have controlled radiation patterns and have throw since they couple transducer to air column.
Recommendations for speakers that sound great at lower volume levels.
I have a pair of Harbeth SHL5 Plus and they sound wonderful when I crank them up. But at moderate to low volume levels they sound disappointingly flat and unengaging - instruments are less palpable, bass has less bloom, and soundstage has less air and dimensionality. I drive my speakers with a tube integrated - a Line Magnetic 845 rated at 26 watts of power. My Harbeths are rated at 86db. Would a higher sensitivity speaker be helpful? Or how about a good quality small shoebox sized pair of speakers coupled with a subwoofer? Or not. What speakers are going to deliver music you can feel at low volume levels? What say all you wisened audiophiles?