How do you know when a stereo sounds good?

When all the types of music that you play sounds good to you. 

Jazz. Classical. Rock.  Pop. Whatever 

When your system can play it all convincingly 

When I am enjoying the music and not the system. A lot of people will refer to this as “when the speakers disappear and all you hear is the music ”. You sound like you are entering the cheating stage of audiofile. You are in love with music but a new sexy “system” is giving you a look and you start to wander and think that an affaire with “system” will be fun and “music” will never find out. Don’t overthink and and step over to the dark side. Enjoy the music and appreciate what you have.

When what you hear makes you realize just how brilliant the music and musicianship are -- that the skill and artistry of composers and musical performers sufficiently justifies humanity, despite so much of all the rest.

Of course, the music and musicianship need to be pretty great for that to happen.

hilde45

You said: "It's like asking the question, "Am I in pain?" That's not a question I can make sense of without some kind of science fiction scenario." Can you elaborate on that paragraph? I don't understand what you are trying to say. I know I'm in pain from the time my feet hit the floor in the morning, but that's from playing competitive basketball for 40 years.

Oh I see. Appears the point of this thread and loaded question apparently was to assert what we like is completely subjective which means anything goes just because. Got it! Mr Denney and his Synergistic company got that covered in spades! Where can I buy the stock?