adding a wired remote volume switch

Great. Got it. You have already given this more effort than I could have expected so I went ahead a drew up what I think you were going to do. Maybe you can check it.(Pic is tacked on to the original album.) Also think I may have stumbled across what might be a cute little trick by way of a stereo pot WITH on/off switch. Along with the 271-1732 I picked up a 271-0215. I noticed there is a perfect little hex drive on the back of the 1732. I plan on cobbling up a coupler to drive the 0215. Waa-Laa... an endless supply of 100k ohm stereo pots WITH on/off for under 8 bucks! You can see pics of this on that album too.

I just realized we may have a tiny problem. You will have to completely disconnect the power switch on the main volume control, remember I said either switch would turn the unit on. And either volume control would control volume up to the level of the highest set volume control. With the radio control off, the volume will be at 0. You will have to keep volume up on the radio volume control. This will have the power switch always on. You will not be able to turn it off via your new switchometer. You will have to cut the red and orange wires and run them to the new switch. If you do not want to cut the wires, you can solder wires to the connections on the bottom of the board and cut one of the traces going to the switch on the radio board. Also you should use a couple of zip-ties to secure the shielded cable to the board of the radio. That cable is not very tough, just the moving around while mounting it will likely break the wires at the solder connection.

I was wonder'n about your original idea of off/on. This one I get. Armed with all this info I will get to work and see if I can make it all happen. Will let you know what the outcome is if you would like...