Im planning to add 2 new amps and a dts decoder to my stock sytem. Is this possible to keep the navi voice and the stock sub functioning as usual.

This is what im thinking of doing. Cut the 8 speaker wires and use a 2 channel line out converter to connect between the HU and my decoder. The decoder Front/Rear/Center go to a 5 channel amps for front L/R, rear L/R and center channel. The sub pre out from the decoder go to the second amp for the 2 12" sub.

Will this work?

Also is the 2 channel LOC has 8 wires to connect to the speaker wire from the HU and has 2 RCA to go to the decoder
I need a LOC that connect to the 4 speaker pair from stock and convert to 2 RCA for the decoder.....