Will this setup work?

I have been doing my research and I just want a decent audio system. My car is equipped with a JBL amp. My setup would consist of replacing the front and rear speakers. Fronts would be components and rears would be something better than stock. I would then be getting the audiocontrol LC7i and the NVX MVPA4 micro amp. This pretty much bypasses the JBL amp. Will there be any issues such as navi or BT audio? I was thinking to cut the speaker wires prior to them going into the JBL amp. Wire speaker wires into the LC7i and connect the rca cables to the NVX. Cut the output speaker wires from the jbl amp and wire those into the NVX output. If this works what can I do to add a small sub in the future? Should I just get a 5 channel amp instead?

 

I know my system won't be a 1k system but want something better than just replacing speakers. I want a clean easy system.