Should I ground my amplifier?
I opened it up, and started looking at the parts. The connections are old-school, first time seeing those. I noticed that one cable was not connected, so I took care of it, and tried to power it up. For my surprise it worked, and I had to secure the plug, which had only red and black (+ & - I guess).
Fast forward to now, I heard or read that anything connected to a plug should have the ground as well, especially if it had something metal. The amplifier is made of metal on the sides. I'm giving it to my uncle, but I don't want to give him in a dangerous state, so, should I change the plug again and put one with the 3 wires? How or where do I connect the ground? (I saw one connected to a screw in the metal part once) And most important, why?
Thanks a lot, sorry for length and for possible grammar or vocabulary mistakes.
TL;DR: Found an amplifier without plug, should I put one with ground? How? Where? and Why? THANKS!!
I've got answers saying that ground on audio systems are complicated and I've been reading but it's so confusing, and I don't understand it pretty well...
THANKS IN ADVANCE TO ANYONE GIVING ME SOME INPUT, I REALLY APPRECIATE IT!! :D