Using line output converter to install subwoofer on stock radio?

I would like to keep my stock radio but install an amp and subs. I have a line ouput converter to do so. But my question is can I just hook it up to the 6x9 speaker(s) in the trunk and plug the RCA cord into the converter and then the amp? Would I be good to go by doing so? I want to awoid touching the stock head unit at all costs cause it's still under warrenty. If I can do this with the speakers in the trunk would k have to tap into both of them or just one?Using line output converter to install subwoofer on stock radio?
Yes that's ok. If you have one Sub, then only use one input on a mono amp.

If you have a pair of Subs %26amp; 2 channel amp, then use 2 inputs (left and right).

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