Entertainment Center Wiring

[Woolibaar]

Whoever had the trailer before me screwed up the wiring for the speakers and radio/tape player. Lamp cord used to connect wires, wires all the same color, two wires wrapped together, etc.

When I got into the cabinet and corrected connections, three of the connectors on the plug don't have wires in the mare's nest of wires left by the previous owners.

So, my question is, is it possible to run the correct 12 wires from the converter to the opposite side where the entertainment center is? If it is possible, is it easy? I would like to use some of the entertainment centers functions, but right now it isn't even possible to even get power to the unit.