Long reply, but it does not answer the question.The full set up is 2.1 lm3886 based system. The scheme is
1. Two core shielded cable is used from rca to tone control. At RCA end shield of cable has been used as common for ground. Both -ves from rca are connected to shield wire. This three input goes to tone control which has 3 pins for input. Tone output has 3 pins two for each amp and one ground. Each amp is receiving two wires (signal+ground) from tone control output. Also three wires go to subfilter two for signal and one for ground.
2. Each amp is receiving two wires of power supply from from main psu. And at output of each amp signal is going to speaker protection. Also output ground from each amp is connected to ground on main psu. For subamp, two wires go to subamp from sub filter. Both subfilter and tone control are powered by a small psu (getting power from main toroidal xformer). Speakers and subwoofer protections are powered by a another small EI xformer.
3. After protections outputs go to final terminals connected to spekaers and subwoofer. The grounds of output terminals are connected on main psu.
4. There is another small EI xformer powering the switch.
Now I hope everything about the layout is clear.
nor confirm that your input wires meet thisBut I also see some "single wires".
What are they?
The barrel of the RCA is part of the Input Signal wiring. This part of the Signal wiring must not be connected to the Chassis. RCA wires (two per channel) go straight to the Receiver input pads/pins, either as twisted pairs, or as coaxials.