The Best Sounding Systems can Play Loudly with Low Distortion

Indeed. The problem of course is you don't really know how loud your system is playing if there is no distortion. A DB meter is handy. At work we used to have a 1% THD button on the test kit. It always made the listener perceive it was louder.

I recently heard a massive Klangfilm system centered on Bionors. It had an ease and seamlessness that made listening unfatiguing at much higher volume than I do at home. But the room was expansive, huge; it had a natural decay that did not interfere with the sonics. The system is far different than the inert boxes delivering a forensic "audiophile" sound with all the attributes-- really more like a giant wave, on a huge scale, that was faultless in tone, dynamics and range. Very interesting experience for me despite my many years at this-- not something that would be easily achieved given the the components or the level of attention required to operate and maintain such a system. Absolutely glorious to hear though!

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

Well stated. I have never even striped to fin how loud my system will go, but I am confident it would be clean and clear all the way. The room would overload quickly though.

My system is capable of playing loudly, but my ears don't care for it.  Back in the day, I played music rather loudly, but not anymore.  When others want to hear my system, they often want me turn it up beyond what I prefer.  

I would add good source recordings, a large room, high ceilings (also help) to that statement, then, you can play loud all night without fatigue.   Drinking also helps, lol..  However, there is still no guarantee that your ears will not be ringing in the morning.