Hi,
If you read the datasheet for the regulator it's warned about there:
8.1.2 Raising the Output Voltage Above the Input Voltage? Because the output of the device does not sink current, forcing the output high can cause damage to internal low current paths... this diode, low current metal, and the regulator are destroyed.
I don't know how much current it can take, or how much current the rig would draw while connected, but a diode might not be a bad idea.? Just to be on the safe side.
73.
