Over the weekend I installed a sub/amp combo via line level converter... I am keeping the stock radio, and I want to upgrade the 4 door speakers, and amplify them with a small 4 channel amp ( again, while maintaining the stock HU) What device is available to enable the use of the 4 channel amp, using another line level converter AND... still keeping the factory amp hooked up the the under seat mid-drivers. If at all possible, Id prefer to not have to run separate speaker wire to the the new door speakers. Any help is appreciated!