If connecting 2 RELs, Connect the black wire of each REL to a ground lug or a chassis screw of the corresponding amplifier channel; twist together the red and yellow wires of each REL separately and connect each pair to the positive speaker terminal of the corresponding amplifier channel. In some instances, this will result in exceptionally high gain (output) from the RELs. If it seems simply too high in gain, please remove either the red or yellow wire from the twisted pair. This will reduce output by half and restore a natural dynamic. If hum occurs try removing the black wire and using the LFE/.1 input for your ground. Connect a RCA cable between an unused preamp output and the LFE/.1 input on the REL, then turn the LFE/.1 volume all the way down.