Derrin Nauenforf, "Ghost Town" Live At The Boardwalk and JJ Grey & MoFro, "Lochloosa" Brighter Days. Those are my go-to tracks.
Honorable Mention: David Bowie, Ziggy Stardust "Soul Love"
Only two tracks to test your system, forever!
If you could only use two tracks/songs for the rest of your life whenever you wanted to test a change to your system, what would they be?