I am going to be using an aftermarket Head unit and aftermarket amp for subwoofers only. I will use the stock amp for the rest of the speakers.
Since I already need the "amp on" pin for the stock amp, what do I do about the new amp? Can I just splice the new amp's "amp on" cable with the old "amp on" cable?

Also, I have my battery under the front hood; how should I run the positive cable for the new amp? If I'm running 600 watts, is it safe to splice into the old amp's positive power cable?
thanks