1. Do you use the LED-1 controller instead of the PSU provided with the units?
no, you need both, the controller is inserted between PSU und LED
Can you controll 2 aquaray500 units with one LED-1 controller (I have 2 twin units so I have 4 units with 2 PSU)
no, for each LED you need one controller
On the LED-1 there is the cable going out and a recepticle market 0-10V. What is it used for?
the outgoing cable is plugged into the PSU, the 1-10V is the control line (brightness) which is connected to the ProfiLux