Judahs units run on 9 V DC, centre negative.
The Kedem 6 and the Kedem 4 each draw 250 mA. That number matters when a supply’s outputs are rated individually rather than as a pool, which most isolated supplies are.
Three things worth writing into a board post:
The supply, and the rating of the specific output feeding each unit.
Whether the outputs are isolated from each other.
Whether any unit shares an output through a daisy chain.
A controller that reboots when a loud passage hits, or a display that dims under load, points at current before it points at the unit.