Sometimes you notice really cool details when reading user manuals. I was checking out the alpine type r amps for a customer, looking to do a 3ch type configuration with his pickup. Anyway i came across this and thought it was super cool. https://support.alpine-usa.com/products/documents/OM_R-A60F_R-A75M_EN.PDF I thought this would be helpful to the beginners, and neat for anyone who already knows, of the basics of how an amp is wired for power and how that really works as a circuit in your vehicle.
One thing to point out is that the amp grounds through the chassis/body/frame/etc and then comes back up to the battery through the negative wire on the battery thats also connected to the chassis/body/frame/etc. A lot of times people will overlook the batteries ground. Its so important, don't overlook the battery ground! This battery ground is every bit as important as the amps ground itself. Anyway just wanted to share! Don't forget to RTFM - Read The Fantastic Manual!