The attenuator and the load box do not need the power supply - Torpedo Captor
The Torpedo Captor is a reactive load box with a built-in attenuator. To work, the load box and the attenuator do not need power. To keep the unit at the right temperature, there is a fan inside the Captor, powered by the incoming amp signal.
The LINE (dry) output does not require power either to send signal out of the Captor.
(The load box and attenuator part of the Torpedo Captor X also work without power.)