Its not a low bar its what is the reality of what you are hearing. Having heard music in a wide variety of environments , One can understand what the instrument should sound like. I sponsored a classical music series for 4 years here in a small venue ( about 500 seats) we had many solo instruments or small goups of instruments. We heard a lot of piano, I sat up close ( I was the sponser after all LOL) and I have then heard the same instruments in Hockey rinks , Football stadiums and concert halls around the country. This is all information fed to our brains and some of us can use such information to understand what it is we are listening too and try to do that in our homes.
When I set up speakers I use my experience and my knowledge to know when they are in the correct place such that the instruments sound correct. The right size, the right sound and that is from listening to them live.
There may not be an Absolute Sound but there sure as hell is the absolute sound I recognize as a piano. Not one piano, not the same piano, not just a grand piano, not just an upright piano, not just an electric piano but the sound a piano makes and the differences we hear when they are played by different musicicans in different locations.
I am not a paralysis by analysis person and I really do love music the rest of this is really mind numbing excercises to exert dominance. That IMO serves little pupose. But heck , Enjoy!