harman cardon rubbish

Hello all,
The Hardon BAD Karma stereo in my rangie has packed up, i've been told it's the amp but they're well expensive!!! does anyone know how to wire in an aftermarket system? i would really like to keep all the door amps and stuff working cos they sound lovely,(when it works) is there any way to just replace the amp with an aftermarket one?
Thanks for any help guys.

Dan

Thought about just having yours looked at? I assume you mean the head unit. They're known to give up around this age and there are a number of places out there that can fix em. Although when it happened to me I was able to get a used one of from a salvage so didn't have to bother.