Do I need more than 1 stereo interface?
This interface seems to be used for the stock head unit when adding an amp, but this interface doesn't fit JVC plug.
So I'm thinking of trying the following: return the PAC GM1416.
Purchase the RP4-GM31 to retain all chimes and steering wheel controls.
Utilize the the RCA outputs on the back of the head unit to feed the amp and from the amp feed the speakers.
Or will I need another interface for the amp?
I believe the RCA outputs on the head unit are line level and not speaker outputs. The harness for the headunit does show the speaker wires.
It sounds like you have a line output converter hooked up to your amp now, by using the hu you will get a much better sound unless you have a lc8 or some other quality line driver.

