Hello,
I am looking to add a pioneer amp GM7100-M and separate subwoofer box to my new Mazda3i. I don't think the factory radio has preamp outs, but I don't want to put in an aftermarket head unit. I know that my amp has speaker level inputs. I have no idea how to wire this setup though, or if it will even work properly (I KNOW it wouldn't be the ideal sound, but its all i can do, if I can even do it). Please let me know if I am headed on the right track, and if possible, how to wire this setup! (Also, would I lose one of the door speakers in wiring up the amp?)

Also, if by chance I am able to make the first part of this setup work as listed above, would I also be able to power the rest of the factory speakers through the amp too, or not?

Let me know if you have questions about what I'm trying to do, I will clarify!

Also... will this modification void my factory warranty on the car??

MANY THANKS in advance for any help anyone can provide!!!

If you want to add an amp to a factory system it is simple. All you have to do is tap into the wires going to two speakers, left and right. The rears will be the easiest. You also need to make sure that the positive and negative sides are correct before hooking up to the amp on the speaker level inputs. There is no need to disconnect any existing speakers for the amp. I would advise to use two channels when using a sub, it is best to run bridged.

I would not amplify the factory speakers as they are already matched to the system and will most likely blow.

If you are not familiar with wiring up a system I would leave it to a pro. It may cost a lil bit up front, but will be much cheaper if you blow up something in the car.:D Warranty will not cover these mishaps.