One comment - the perfect pitch exercise becomes a relative pitch exercise as soon as you get one note right. I don't believe I have perfect pitch but I got 100% on the quiz I just did.
I don't think it's a crackpot theory. The basic idea is that the gauge group is the group of rescalings of the units of money, and arbitrage appears as curvature in the gauge field, i.e. you end up with a net change when you parallel-transport money around a loop in the (discrete) space of assets and time.