It seems one of the great mysteries is how we get from the 120 volt AC coming out of the wall socket into music playing on our loudspeakers.
I was going to write that you cannot plug a speaker directly into your home's AC power outlet until I remembered that's exactly what JBL used to do. To get enough power to test one of their massive woofers, engineers at JBL were rumored to have simply plugged it into a 120 volt outlet so it would produce a very loud 60Hz note.
Definitely not something you should do at home!
JBL engineers aside, the art of taking power from the wall and converting it to audible music is a lengthy chain that begins—and mostly ends—at the power supply.
As I have written in the past, the job of the power supply is to straighten out the 50Hz or 60Hz AC in the wall. What we want is a steady + voltage like that from a battery. From there, we use our transistor or vacuum tube valves to connect, in varying amounts, the power supply to our speakers.
It's really that simple and I think the confusion or misunderstanding folks live with can be found in the notion that output tubes or transistors "deliver" or "produce" power to the speakers—something they certainly do not do.
If we can wrap our heads around the idea of tubes and transistors as valves connecting the power supply to the speakers we're going to have a much easier time turning that proverbial light bulb in our heads into an aha! moment.