I made a splitter lead. I already had an ISO -> ISO wiring adapter (with the memory/ignition wires crossed to make up for VW's desire to deliberately break standards). I wired in the additional ISO plug, connecting the memory, and illumination wires directly. The ignition wire is connected to the head unit's power aerial output so that the Empeg always comes on and off with head unit, even if I turn the HU on manually.