On Mon, 6 Mar 2017 09:58:41 +0100, Dominique Michel wrote:
You must have 1 connection to the ground, and all the
equipments must
be connected to it.
Instead of following you wiring hints, the OP should follow my hint
to connect the computer and amp to the same main socket by a multiple
socket, ensuring that the main cables and audio cables are 100% ok.