There was some recent discussion about tracking down "phantom" power draws, including the radio unit which uses power in standby mode. Personally I just wanted to be able to turn it off entirely as we rarely use it, and I don't like the light from the clock at night (plus the clock is never the correct time anyway). Pulling the fuse triggers another LED on the converter, plus we do want the sound system to be able to work occasionally. I previously pulled the TV out completely, so this is just for the radio. It is not difficult. In case you have little or no knowledge of this type of thing, here are some step by step instructions.
1. Turn Battery Disconnect to OFF with red knob
2. Gently pop off the bezel around the radio. Pry with something thin and plastic.
3. Remove the 4 square head screws and carefully pull out the radio and wiring.
4. You will need to find the wago connector with the red wire that is labeled "+12V DC Switched"
5. Lift the tab and remove the red wire. You will need to go from that wire to a switch, then back from the switch into the same location in the connector. I.e., the switch will be able to interrupt the 12v power to that connector.
I used a switch I had on hand, and decided to put it in the storage box behind the radio. Any light duty switch should work fine you can find something at the hardware store or Amazon, or harvest from some old electronic device. I drilled through from the storage box into the radio cavity -make sure the wiring is out of the way. Depending on your switch you will have to decide how it mounts. Mine had a threaded retainer, and I filled in around it all with hot glue.
6. Attach 6" of flexible wire to the switch. Use a wire gauge similar to what you see feeding the radio. 16 AWG if you are going to buy some.
7. Mount the switch
8. Connect one of the switch wires back into the wago 12v supply connector. Connect the other switch wire to the red wire you removed from that connector, the one with the +12v sticker. Its best to solder the wires and use heat shrink tubing, or use a crimp connector, or you could use a small wire nut and wrap a bit of electrical tape around it.
9. At this point I would turn on the power and test, then turn off the battery power and put everything back together.