It doesn't mater what head unit you have there is 2 ways to send a signal to most amps
High level
&
Low level
High level: they use the signal from your radio through your speaker wires but your amp has to have a high level input! They look like an 8 pin harness that would hook up to the back of your radio but it plugs into your amp. Now this is what you will need you can splice into your regular speakers wires in order to get the signal to your amp and still retain your inside speakers.
Low level: these are your typical RCA jacks
follow the link this may give you a better understanding or ideas on how to wire it different ways.
Good Luck