I just recently purchased a 4-Channel Kenwood KAC-8404 Amplifier and Kenwood KFC-C1739ie 6-3/4" 3-way Speakers, I already had a Kenwood KDC-BT645U Head Unit. My goal was to have the Amp power my 4 Kenwood KFC-C1739ie 6-3/4" 3-way Speakers, with my Head Unit. But when I was trying to install the...