Installing line output converter to Stock Headunit

[xtullyx]

I have a 4dr 2002 honda civic and im trying to install a pac 2channel converter.. it has 6 wires white, white and blck, grey and grey/black, with 2 red ground wires. I'm not sure which wires in my harness are the rear speakers, and there is very little play in the wires connected to my hu to splice them and connect them to my converter

[xtullyx]

Do i need to connect the ground wires?