many great responses here.
I have always had an issue with the "live unamplified music" being the gold standard. As mentioned in previous posts, a lot depends on the venue, where one is sitting, etc.
I have attended several (more than I remember) concerts. Jazz in small venues (best), Jazz in large venues, classical, rock, etc. most concerts (not all) are amplified. even in small venues. So, unless one is sitting right next to the stage, you are hearing the music from amplifiers and speakers, and that is dependent on the sound engineer.
But, small venues, up close. wow!.
Examples are Shirley Horn everytime she visited LA, I would go see her. What a treasure. So sad she passed. It was just her on piano and vocals, with her drummer and bass player. wonderful. Could listen all day. Eliana Elias also in small venues is wonderful.
Pat Metheny group when they were together was great. at least three hours performing. no talking. Amplified, but the performances were great.
To me, listening fatigue is dependent on the music and recordings, and the system.
One can only take loud for so long before the system starts to shut down to protect itself. Bad recordings are another cause of listening fatigue.
I'll take Jazz recordings from the mid-to late 50s, sixties and early seventies any day.
Another issue is knowing what to listen for and for me, making sure my system can accurately reproduce the recordings properly and also accurately showcase instruments correctly. I've played classical violin, and several other instruments. I know what a real (non-electronic) violin, piano, etc. sounds like. So, when I listen to systems and the instruments don't sound real, it drives me out of the room.
Same with bass. If it is too much and not accurate or boomey. I can't deal with it. Bass reproduction should be accurate, not exaggerated. Some equipment emphasize bass to the point that it isn't what was recorded. And people listen to it and say, boy, that bass sounds great. others listen and say, that's not real, that is exaggerated. The system, including the room, should be flat in frequency response from 20Hz to 20kHz. one can tune the system and room for certain taste, but peaks and valleys are what one should be trying to eliminate unless there is a hearing issue where equalization is required.
to the OPs original post. I can listen to my system for many hours with no issues. I know and hear the differences between certain artist and their instruments. certain violins, certain pianos. Joe Sample vs Bob James, vs, Bill Evans, etc.
So, "live" does not mean accurate either. especially if "live" is amplified. I've been in really small venues where the artist were still amplified and sounded like a mess. Shirley Horn live at Vine Street. Well, I was there. yep, the recording sounds very much like the live event.
For me, it was me trying to get to that "I'm there" moment with my system. No need to upgrade (unless I was given a piece and price I couldn't walk away from). Randy at Optimal Enchantment in Santa Monica was very good at that.
Better equipment out there. you bet. But, does my system in my room sound great? yep. Does it sound like live? depends on the recording, the miking used, etc. Early CD recordings sound terrible. Music is great but the recordings were terrible. Stanley Turrentine (Don't mess with Mr. T). Great music, horribly recording LP. OMG.
enjoy