Do we really know what "Live" music sounds like?

I would think that older people know...

When I was really young I played at recital competitions (clarinet) and my sister played piano in the same (she was good).

In these cases the audience always considerably outnumbered the players.

Later on when I was 10, or so, I played guitar with a local Blue Grass band @ local "coffee houses" and none of the instruments/vocals were amplified (including bass guitar).

Once again the audience greatly outnumbered the band members.

Added to this are the numerous band/classical local performances I recall from my youth.

Much later on, but long before "unplugged" became a thing, I also listened to various acoustic/non-amplied performances in the greater Los Angeles area.

In the late 70's I was waiting for a dinner table @ a local restaurant and Herbie Hancock played a few improvisational pieces on an upright piano they had available (he was also waiting for a table:-).

Never cared for his electronic keyboard stuff up to that time, but he was awesome on the acoustic piano, just doodling away.

Anyway, musicians often have audiences that HAVE experienced non-amplified music/sound.

DeKay

Live music sounds an almost infinite variety of ways. Even the same room will sound different based on the number and location of bodies and furniture, the temperature and humidity level, the instruments being played, and the way they are played by the musicians.  

Kind of a bogus question. My music is different than yours so you can’t say music is only un-amplified. My music is all amplified and I have spent decades playing music in different bands, so I know what certain instruments should sound like.

99% of the concerts I attend are outside and quite a few of them you can hear the guitar thru the fender amp, others you hear everything from the PA system.

You bring up mics/pa systems, how about the room/hall/arena you hear the music in? That makes a huge contribution to the sound. 
I would take a concert in a great amphitheater that is amplified instead of an orchestra concert in a concrete building that is not built for good audio

Spent my entire childhood singing in groups and choirs un-amplified music. A choir doesn’t require application if the signers are taught correctly. Attended a church that only allowed un-amplified music (no instruments - voices only) performed by all the parishioners. I also spent time learning to play the guitar and the piano. I had to listen to a brother learn how to play the bagpipes.

I have a pretty good understanding what live "un-amplified" music sounds like. It sounds very different from music that is transmitted through a speaker.

Does a movie sound or look like a play, no.