It happened for me when I was a teenager having my first car's factory head unit replaced. While I waited for the work to be done, the owner of the shop let me hang out in the demo room, kick my shoes off, sprawl on the couch, and watch a Terminator 2 Laserdisc. He selected his high end Paradigm speakers and turned the volume up to 11, Spinal Tap style. It was loud! But it was also clear as a bell -- perfectly imaged, no audible distortion, perfectly equalized, not at all shrill or brittle. It was just a 4.1 setup IIRC. Nevertheless, I've never been to a movie theater that could compare. I felt such a sense of loss when the work on my car was completed and I had to leave. I wish I'd had some music with me to try.
Before that day, I never realized how truly crappy my best friend's Pioneer hi-fi towers were in comparison (which I had always regarded in awe), or how unmusical were my neighbor across the street's bombastic Cerwin Vega towers (capable of rattling the neighborhood windows along with my guts). I thought the mark of a worthwhile sound system was profound bass and the capacity to piss off the neighbors. I didn't know that such a device had yet been invented that could, if you closed your eyes, fool you into thinking you were a participant in the scene.
But owning such sound has always been a pipe dream for me. I've never had the kind of disposable income to achieve that sort of sonic transparency. I think I might be on my way now though with my new Marantz SR6008 receiver and a pair of massive MB Quart Vera bookshelfs I'm due to receive this evening. We'll see.
On the other hand, as a spectator and veteran performer of more choral, symphonic, operatic, and stage band performances than I can count, I like to think I'm not an easy sell. I know what music sounds like live. Now that I know reproduction sound does not have to sound like a reproduction, I may never be satisfied until I can close my eyes and achieve a proper out-of-body experience. I'm just beginning my quest in earnest.