Higher end manufacturers design for 1) the taste of certain audience and 2) signal accuracy. In other words, some high end manufacturers actually modify the electronics to produce a certain "sound" from their equipment. So, you have heard of the xxxxxx brand sound. Some design to accurately reproduce the electronic signal period. Some design to accurately reproduce the electronic signal and to drive specific loads. So, to answer your question "what is a high end stereo supposed to sound like?" well, it is suppose to sound like what the designer wanted it to sound like. I know this appears to be an evasion, but it is the truth. Since the majority of us were not present during the actual recording session, we have absolutely no idea what the original recording sounded like. We can only go by our individual experiences related to music, knowledge of instruments, recordings, and taste. Being an ex-violinist, clarinet player, sax player, oboe, basson, etc. I know what instruments sound like. And yes, even pianos or violins and drums, sound different from others. Listen to Joe Sample play the piano. His piano it totally different sounding than any other pianist. So, when I hear a recording and cymbols don't sound correct, or drums sound terrible, or the violin is horrendus, I know it is the play back equipment, recording, or anything in-between that is the problem. But, when I play that same recording on a really good system and it sound wonderful, that tells me what I want to know. That something in the play-back medium is faulty or poorly designed. So, my reference is a really great system at my favorite stereo store in San Diego. Every now and then I'll go there and listen to music on stupidly, I can't afford it equipment just to hear the recording on a better system. Also, I go to concerts. Outdoor, small venue, unamplified, amplified but small venue, classical, etc. to re-establish my frame of reference and for enjoyment. You want to know what a female singer sounds like? Go to a play, concert, ballet, etc. and listen. Then go home and play similar music and see if it is close. Nine times out of ten, it probably won't be close. Even with modern high end equipment, it still isn't there yet. As long as analog has to pass through equipment and be processed, there will be distortions, errors, time delays, etc. introduced by the processing equipment and the more equipment, devices it passes through, the more it will get away from the real deal. This is also why the typically best recordings are directly from analog master tapes direct to disc or analog tape to digital with minimal processing in-between. but, take your favorite music to really good high-end stores and sit in their most expensive high end room and listen.
have fun.
have fun.