Originally Posted by turbodog

Remember, if doing this with a stock base HU, the rear channels ARE available from the HU, just need to add pins to the vehicle connector. This way the fader can be used to control the amount of rear fill desired. I suspect just wiring them into the stock HU front channel would yield less than wonderful results.... and the parallel connection of 3 sets of speakers might result in dangerously low impedance presented to the HU power amp.