03 impala

am try to install aftermarket amp and sub in my car but keeping factory radio. i know ineed to use hi level converter and butr do i install it before factory amp or afterwards. last where do i hook up remote wire in factory system so i wont hook up in fuse box straight on with swicth any help  will be good thanks

I remember reading some time ago that in factory amplified Impalas, the bass decreases as you turn up the volume.  If this is the case, you need to get your signal before the factory amp.  I believe the factory radio already has high level outputs, so yes, you will need to use a line out converter.  If you can't find a suitable wire to use as remote turn on, you can always run to the accessory lead at the ignition switch.  It should be brown, but test it first.

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My ex once told me I have a perfect face for radio.

thanks for info will give it a try