The Best Sounding Systems can Play Loudly with Low Distortion

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. 

I can play well beyond what my ears are comfortable with and hear no discernible distortion.  Like others I much prefer listening at lower levels, particularly in the late evening when I don’t want to disturb the neighbors, and find that it still sounds outstanding at least to my ears.  Even at low levels, 50-65 db, I get a wide and deep soundstage and proper imaging.  Granted my room is small so it’s easier to do that in a somewhat near field listening environment.

IM with the responses much more impressive is almost silent yet still dynamic.  I actually sit there and grin a low volume late at night listening in the sweet spot and go wow!  That's much more difficult to do then loud without distortion.  I can rattle my floors and windows but that's just in your face whereas low light low volume listening can make the hair on your arms stand up.

One of the best ways to test your speakers is to start playing music at a very high volume and then gradually lower it in steps. This will help you determine whether the imaging, depth, and soundstage (left-to-right and front-to-back) remain consistent. However, the maximum volume you can achieve depends on the room's size and acoustics. If you play too loudly in a smaller room, you risk overwhelming it, which can disrupt the soundstage. Conversely, playing too softly in a larger room may prevent you from experiencing the full impact of the music.

It’s also important to clarify what you mean by "distortion." Distortion can originate from the audio system, the room's acoustics, or a combination of both. Therefore, it’s essential to identify the source of any distortion before seeking a solution.

Yes and, as a result, it is not unusual for the actual loudness to be greater than it seems.