I am still surprised when I speak at events. Surprised by the number of people who find it a revelation to learn that all we hear in our music systems is nothing more than the nasty power from the wall played through speakers–modified certainly–but, none the less, converted from one form to another.
I remember, years ago, JBL (when they made good equipment), tested a particularly stout 18" woofer by connecting its speaker terminals directly up to the 120 volt wall power. That must have been loud. Can you imagine? 60Hz buzzing through an 18" woofer at full tilt! But that's not music (and don't try that at home).
We plug our stereo equipment into the wall socket and it just works. Rarely do we give a thought as to what's happening inside; how does this moving AC turn into the delicately small signals providing nuance to our music?
Let's spend a few days looking into this interesting subject.