I finally happened on it this morning! I was playing along with the metronome and got bored. I started practicing different songs all on top of one another in the same project to the same rhythm.
When I was done, I unmuted all lanes and there it was...
That awesome sound of a bunch of people all playing different songs at the same time.
This was the sound I grew up with! I've heard it at SO MANY jam sessions! That perfect cacophony of madness from people playing songs in lots of different keys all at the same time!
This is the sound of my life.