Cut, splice and tin four pieces of stranded core wire, approximately 90 mm in length.

Solder a wire to each of the four input potentiometer's front output pins.

Solder the other ends of the four wires to a shared row on the perma-proto board. These are the left channel outputs.

Cut, splice and tin four pieces of stranded core wire, approximately 85 mm in length.

Solder a wire to each of the four input potentiometer's back output pins.

Solder the other ends of the four wires to a shared row on the perma-proto board. These are the right channel outputs.

Solder a 1K ohm resistor to each of the shared rows on the perma-proto board.

Cut, splice and tin two pieces of stranded core wire; one approximately 85 mm in length and one approximately 90 mm in length.

Solder the shorter wire to the resistor connected to the right channel outputs. Solder the longer wire to the resistor connected to the left channel outputs.

Solder the right channel output wire to the main output potentiometer's back wiper pin.

Solder the left channel output wire to the main output potentiometer's front wiper pin.