I guess you figured out your amp only does low level inputs.

Most line level converter are 2 channel but there are 4 channel ones as well. Check out the link below...basically all of the HU highlevel speaker wires connect into the converter.

http://www.scosche.com/scosche/elect...converters.asp

DO NOT COMBINE (BRIDGE) ANY OF THE DECK's speaker wires with each other! Deck amps are not bridgable....very very few aftermarket deck were stable at 2ohms.. older rockford decks were... but anyways...