3 ways:
When it sounds so good I can't help but smile, and sometimes shout OMG out loud.
When a visitor hears a 'real' system for the first time. I love watching their faces, I've even had people cry.
Sometimes I'll buy hundreds of records or CD's at estate sales. I love it when I hear some new (to me) artist that blows me away. I once scored 12 feet of records for $50. Took me over a year to go through them, but my horizons were expanded because music before 1960 couldn't be good, right? Wrong!