Solved! How do I connect a velodyne series II power servo controller and subwoofer to a Sony str-dn840 receiver

That receiver has two subwoofer out RCA jacks you would use one of them or both of them, to the "from preamp" connection on the Velodyne.
 


I guess I don't understand what you are trying to do. The Velodyne controller would have a passive subwoofer connected to it. I already identified how to connect the controller to the Sony.