This modification adds a rear input to a Yamaha DG-1000. The priciples used here could also apply to other preamp designs.
This modification makes use of the existing input jack on the DG-1000 to switch between the rear or front input. Using the front input will automatically disable the rear input. Both front and rear inputs are electrically identical, and in my tests do not affect the sound of the guitar.
To complete this modification, you will need to cut two solder traces on the input card, and drill a 3/8 inch mounting hole in the rear panel. The cutting and soldering are pretty simple, but to install the rear input jack, you need to disassemble the entire DG-1000. This is a fairly easy process, and involves removing lots of screws with a Phillips screwdriver, and disconecting some plastic connectors. But be warned, there are lots of screws and connectors, so patience is required, along with careful documentation so the unit can be reassembled correctly. I have included pictures of my effort for your reference. Also, it should go without saying that this will destroy your warranty, if you still have one. And since the DG-1000 is a digital device, be sure to take all the necessary precautions against static electricity damage.
