How to separate?

hello at the moment I have a 2 way system with a passive soft got me a midrange driver, wants to make a three way system out of it and the whole should run actively but heard that a 3 way system has to be done very well so what sounds like in the car,then I will go to a expert now to my question how do I separate the whole best ? radio (dxz958)?,processor,passive or active soft what would sound be the best solution? mfg