The reference sound is of course always the unamplified live music. Many folks do not have easy access to hearing unamplified and live music, that's another matter. I have written about unamplified live music being the reference in at least 10 posts in HFV.
In India, in most concerts, the amplification and the speakers used for live concerts are horrible, to say the least. Indian music is mostly based on melody and is usually performed solo, and hence unfortunately some amplification is essential in a big concert hall. OTOH, in many western theaters for classical music I have been to, very little or no amplification is used.
As I have written in many posts here, I have had the rare opportunity of listening to live unamplified music. I have heard many of the stalwarts of North Indian classical music of the last almost 5 decades live and unamplified. Sure, depending on the room, the sound still varies, but if one listens to a given artiste enough number of times, one has a pretty good idea of the tonality and timbre. Actually this is the form of live music I mostly listen to, still now (I go to concert halls only quite rarely these days). Needless to say, I have not come across a hifi system or recordings, however expensive, that can reproduce the live unamplified music. But, if there has to be a reference, live and unamplified music it should be. This is what I would ideally strive for in my system.
For some, live unamplified music can be a disappointment, if they are only used to recorded music played through amplifiers and speakers. For them, the live music may sound too uncultured, too bright and too raw. For me though, music reproduced through most systems sounds too polite, too made up and of course compressed. The openness of the live unamplified sound is lost, this is something everybody should be able to understnad, I am sure, once they hear the real thing.
I also think, quality and quantity of bass is an often misunderstood concept in reproduced music, especially with acoustic drums like tabla, mridangam, pakhawaj etc. With reproduced music, many times people hear the room effect more than the actual sounds of these instruments. Bass extension and tunefulness can be quite different with different players from the same instrument (3 tabla players usually come to my place, and they play on the same tabla I have at home and in the same room, and they sound very different tonally). Now, unless one has some experience of all these different sounds, it is difficult to judge the quality of reproduction.
Of course, in the above I have given a musician's point of view. One does not need to be a musician to be a music-lover. And a general music lover does not usually have the opportunity to hear live and unamplified music. Everybody does not have to agree with the view presented here. But being in music and also in this hobby for a long time, I can appreciate some of the views expressed in this thread: some of the priorities of music reproduction seem to have changed over the years.
Regards.