The Best Sounding Systems can Play Loudly with Low Distortion

All subjective. Some people don't like to listen loudly.

Totally agree with @ghdprentice "Being fully satisfying at low levels is a much harder feat and is the mark of a truly great system..."

Recently upgraded my KUZMA STOGI S Tonearm to a KUZMA 4POINT9 Tonearm and one of the first things I noticed is how well it played at low volumes. I own a  Audio-Technica AT-OC9XSL Dual Moving Coil Cartridge with Special Line Contact Stylus and was looking to upgrade it until someone more knowledgeable than me told me that no cartridge upgrade would come close to what I would achieve with the cartridge I own mounted on the 4POINT9...

A lot (most?) of us were exposed to loud stereos before we experienced good stereos. At an early age we learned to equate loud with distortion, and can hear surprisingly loud, distortion free music without realizing how loud it really is. We don't get the signals that originally told us it was "loud". That was an interesting discovery for myself and several others over the years, and probably contributed heavily to my tinnitus. 

Not convinced that low distortion equates to a very low black noise floor or higher fidelity.