An unlimited number of dimmer expansions can be connected with a flat cable (you can find it in this shop, too) to the dimmer board. The dimmer board sends the brightness signal via the cable to the expansions at which you can connect the lamps (max. 12 V, max. 5 A) and their power supply (max. 12 V) in the same way as to the dimmer board.
With that you can control with one potentiometer connected to the dimer board an unlimited number of sub-dimmers with different voltages.
All grounds of power supplies of dimmer and expansions have to be connected to each other.
Ready to ship in about two weeks.