Where Does Clarity Come From?

[Dyno]

I listen to music on three systems -- one car with the optional Harman Kardon system, another car with a Bowers and Wilkins system, and my modest Yamaha/ Klipsch bookshelf system. My favorite is the B&W system, but I'm not sure what makes it better, except that everything seems cleaner and clearer somehow. The frequency responses of the B&W system (green line) and my home theater system (red line) are system below.

I may have found part of the reason why the car system sounds better... VOLUME. Before I started my pink noise RTA recording in the car, I set the volume to the "Dad's rocking out" setting, approximately 80 dBA on a favorite tune. OK, fine. But, when I went inside to repeat the measurements at the same volume in my home, all I can say is "Yikes!". I'm glad nobody else was home. The windows were rattling. I'd never listen at that volume at home.

It's often said that the music seems to "open up" as you increase the volume and I seem to be much more comfortable with high-volume listening in the car. That may be one reason it sounds clearer to me.

What else contributes to clarity?