One thing I’ve had happen live that I’ve never had happen with a sound system is the music taking over and transforming the space - at least in my mind. I went to see Isaac Stern at our local Hult Center for the Performing Arts. It was just him and a pianist playing duet. He and the pianist came on stage, talked a bit about the works they were going to play, did a little tuning, and then started in to it. With the first few notes, I could almost see something settling down in the concert hall, a magical atmosphere. It really shocked me! The concert hall was transformed in a matter of seconds, felt like I was in a different place and time.
Something similar happened when I was in middle school. A quartet from a University stopped by our school and performed for us in orchestra class. The effect was almost too much for me. I was overwhelmed with emotion, literally trembling by the time it was over. I was trying to hold it together, embarrassed that tears might start flowing in front of my classmates. I recall they played something by Dvorak.