Pictured is the PinWoofer SAM 12V Power Cable.
Under the right flipper, locate the spare 3-Pin Molex connector.
Connect the PinWoofer SAM 12V Cable Harness to the spare SAM connector.
Shown is the schematic origin for this connection.
Plug the 3.5mm power plug at the opposite end of the cable, into the PinWoofer Amp.
Pinwoofer TM - ID § 48-501