Audio Systems: 2004 sierra bose system, bose amp, bose system

Question
I am adding an amp and subs to my 2004 gmc sierra ext cab.I have the bose premium sound with steering wheel controls,onstar and xm.I would like to keep the stock radio I know the speakers are nor individually amplified(there is a seperate amplifier for the bose system.I have a line converter,where do i splice into the rear speaker wires before or after the bose amp?And what are the wires to splice into.I appreciate any info or assistance with this matter thank you

Answer
Hi o'neil!
You should splice after the amp if you're planning to use the  line converter (high to low) some converters have two channels , use just only one (going to only one speaker line) and add a "Y" RCA connector at the output to feed both channels of the amp.