Hello, to sum up my audio situation first hand, I have a 03 Mitsubishi Eclipse with a 6-way speaker system (typical 4 plus tweeters and dash speaker) from factory, and a factory amp underneath the passenger seat. Upon installing a Alpine head unit, I used a harness adapter to make it work with the factory amp instead of hardwiring the individual speakers to the H/U.
Now im installing subwoofers and a amp, the subs are 200 running watt, and there is two connected to a 400w amp, the amp and subs are kenwood. The amp powered up and subs got signal, but I noticed they were extremely quiet, and that was with the input sensitivity on max on the amp. My Alpine head unit has a feature called Power IC, where if its on, it stops using the headunit amps I believe. Upon turning it on, my subs got louder, so I think if its off, they are getting the power from the amp they are connected to like they should. However when power IC if off, my other speakers dont work, so its like im choosing subs or the other speakers. To sum up, can someone explain why this is, and how to make it so my subs work correctly in conjunction with my car's regular speakers?