It is good to talk on motivations and fundamentals of our audiophile hobby... Too many posts, was basically able to read the beginning of this nice thread.
I agree that subjectivity factor cannot be ignored, we may perceive things in different ways dispite that our basic perception organs are working similarly. It also depends in which mood are we currently. And one cannot ignore the music itself. There is music that makes one feel good but doesn't somebody else, and visa versa. What matters finally is which kind of feelings provokes in you certain audio equipment while auditioning certain music.
In practical terms, I would say that one's audio equipment is "musical" if it allows to experience the best feelings that one is able to experience auditioning a particular piece of music. As in love we associate our feelings with a particular personality, we may associate a particular audio equipment (and a piece of music) with musicality. A musical equipment would maximize the positive emotions that one is able to experience while auditioning certain music. The musical equipment would make you feel completely satisfied.
And it was said a lot what technical features a musical system should have in absolute terms. Still, some of these "absolute" features may not be that universal but can rather can be subjective.