2005 Silverado Bose line out converter

My 05 Silverado that has the Bose system in it already has an aftermarket amp and sub installed. The person who installed the aftermarket amp and sub before I owned the truck used a line out converter located under the console cup holders and tapped in to the wires there to get the rca's to the aftermarket amp. I know the Bose system converts the signals somewhere along the way and I feel like where the line out converter is located, I might be getting a degraded or some sort of Bose processed signal? Would it benefit me at all if I were to install a PAC audio some-gm24 directly behind the stock head unit? Or the PAC audio C2A-GM24 amp add on interface? Would this give me an un-processed signal for the sub amp? Or am I waisting my time?

Wasting your time.