The Absolute Sound vs Pleasing Sound

"No system sounds exactly like live music and none ever will; but some get surprisingly close."

Do not forget that some (most?) of the current live music/events are also playing through the electronic system. When listening to, let’s say, rock’n’roll and trying to have it sound like a live event, you are really trying to match that electronics/venue combination.

Having said that, there has not been much live music to compare our systems with lately.

Excluding your last sentence, which will thankfully not be applicable for too much longer, what you correctly point out is the reason that unamplified acoustic performances remain the standard for judging how close our systems get to the sound of live. As I’m sure you know that was the basis for the term “the absolute sound”.

Live like sound is always what what I find most satisfying. The more live like the better. It’s why it seems no conventional speaker can ever wean me off Ohm Walsh “Omni” speakers.   Everything sounds live to some extent, not like a studio recording. 
I find conventional box speakers that feature very wide dispersion can come close. The kef ls50 metas (+ powered sub) I added recently are a good example.

"...unamplified acoustic performances remain the standard for judging how close our systems get to the sound of live. As I’m sure you know that was the basis for the term “the absolute sound”..."

Indeed I do but that is about .01% of the type of music I listen to, so why use that as a standard? 

Frog, how are you ?
We always have an unamplified instrument with us - voice. If system doesn't reproduce voice reasonably well it is no good.
Record your voice on tape and play it. Next step play an acoustic guitar, just strike a few accords, record it and play.
If you only listen to amplified and 'synthetic' music, that's easier, though still it is hard to get dynamics right in a small room, and almost any room is small.