Power switch for sub ( modify existing sub )  

The power switch is usually the first thing the hot leg hits once the power cord is inside the component.

Basically, what you usually see is the power cord coming in and going straight to a transformer. The hot leg will be interrupted by a switch.

Since that isn’t happening with your sub, to figure out which of the two is the hot leg, notice that the outer insulation on two conductors of the power cable are not the same. One will have markings down it, or perhaps it will have a ribbed surface down its length. Once you’ve established which of the two conductors is marked, and how, go to the plug end and notice the blades, one is wider than the other. The narrow blade is the hot leg. You should be able to figure out from there which lead is the hot lead, and how it’s marked. Then find the same lead on inside the sub, cut the wire and install your switch across it (naturally, you want to make sure it’s unplugged from the wall). You can probably find a blank area on the connection panel to drill a hole for the switch. Get a switch that takes slide-on connectors that are crimped to the wire. You might have to lengthen the wire to reach to where the switch is.

Regards,
Wayne A. Pflughaupt