you need to get an inline converter it is installed inline with your rear speakers and will not rob them of any power, the other end has RCA jacks to be plugged into the input of the amp for the rear subs. I had one with my shaker 500with a 600watt jbl amp & two 10" Jbl subs one ported and one not. The sounded great. Now I have the z3 and have the subs run right from the rca out from the reciever, that way I can control the level and frequency also a great sounding setup. You can get an inline converter from any car stereo shop or Best Buy.