Hello I would like to know what I need if I want to switch from an ETON ECC 300.2 to an ETON EC 500.4S. I change because I still want a subwoofer.Currently the front system is on a 2 channel.Now I want a subwoofer,and therefore the switch.I need now only a 4 chinch cable,and I clamp it to my car radio and the end of the amplifier,and then only speaker cable from the amplifier to the subwoofer,or??? buy cable and then the one on the car radio and the end of the amplifier for the subwoofer?Or the cable must be undeserved a 1x 4 chinch.http://www.amazon.de/…/ref=ox_sc_act_title_1?…or http://www.amazon.de/…/ref=ox_sc_act_title_2?…http://www.amazon.de/…/ref=ox_sc_act_title_3?… My Stystem JVC KW-AV61BT ECC 300.2 Pioneer TS-E170Ci MfG