I would run all new wiring if your going add amplifiers and that center Speaker is garbage anyway. I frankly assumed it was just for the Bluetooth, but most head units aren't going to have an out for a center Speaker (it's going to be left or right). I don't know that they make a dual voice coil Speaker that small (that is the only way I know to not only play the 1 channel). There are others that maybe could speak more intelligently on that, as for jumping the factory amp (I would cut the speaker wires at the harness, although if there are no speakers hooked to the other end I guess it wouldn't matter). If you look at the back of your aftermarket deck it will have rca jacks for low level output for left, right, and sub (it may have front and rear too) they are the only Speaker connections you need to an amp. As a matter of fact when the deck is installed, I would only hook up power, ground, and the remote wire for amp (there will probably be a constant power wire too for clock and memory).