One thing that I loved about a good full-range drivers is I don't have to calculate and experiment the cross-over values. But in most cases, the one pair full range speaker cannot give fuller frequency band. Especially for the car audio system, in this listening space, it is require multi driver to reach the full band audio frequency. As you may have the same experience like I did, designing the cross-over in multi way speaker system may takes so much time and money. This is including trial and error from different value of components and hear the effect to the sound. I used to experimented the parallel cross-over configuration for long time. This parallel cross-over means each driver has the same input from the amplifier, configures in parallel. It is more difficult to design, especially if it set into higher order frequency slope. The most problem with this parallel cross-over is the frequency response between the drivers is hard to blend each other ...