Here you go. This is the best treatise on wiring for AV/2-channel audio that I have seen. Basically, it is the wiring scheme I have used for years. This works.
Sharing ground wire between two dedicated circuits
Planning to install two dedicated 20amp circuits with Romex 10/3 and 10/2 Cable. The run is about 70 feet. Have learned that the 10/3 as an insulated ground versus 10/2 which has a ground wire but it's not insulated.
Idea has been proposed to share the insulated ground from the 10/3 wire with the other 10/2 dedicated circuit. Achieves the same thing at a lot less cost? Does this make sense?