What is a high end stereo SUPPOSED to sound like?

It should sound how you want it to sound.

There are many studios that have floor standing monitor speakers(inside recording area) in order to compare sound recorded from each instrument where musicians before recording are being asked to play simple passage individually and than as band. Each time the passage played is compared to the sound from speaker till satisfied. The music instrument or any source of sound in the same room shoud sound as close as possible like sound comming from speaker(s) in the same room.

Pretty simple to judge this particular way and it's way different from "Nothing".

Ain't that Somethin'?

For me, a high end stereo is supposed to sound like music is being played in the room by real musicians, not by a stereo.

I'll buy Foster's answer.

Three with Foster, only it should sound like it's being played in the original venue(ideally, if the microphone technique captured the room acoustic). But then- who am I to say what your system should sound like to YOU?