Actually Car speakers are the same thing as studio monitor speakers. Lets take Polk Audio as an example. I have some polk towers at home, and my x-girlfriend decided to blow up one of the speakers. I pulled the driver out of the box, and it just so happened that our store stocked the same model speaker, since the 2 7in speakers are 4ohm in series it was no problem to replace them with the car drivers. Usually a home speaker has a resistance of 8ohms, while car is 4ohms. Now if you build your own home towers you will need to have 2 sets of components in series, and you will have to build a new crossover network due to the resistance change. The big difference in the polk speakers was the home towers were in a 1in thick mdf box, and the tweeters were recessed so they would time align to the the voice coil of the mid driver. You would run into problems with a coax, because the tweeter crossover is mounted to the back of the tweeter, but the tweeter wires are most likely behind the sticker of the rear magnet. Some co's. have bi amp inputs on coax with external crossovers, and I use JBL Power series coax's in my own towers with custom crossovers when I am not using my mains.
just to give you an idea of my background see pic below, this is my desk when I work at night.
Originally Posted by this n00b again
i've done it before but the clarity of studio monitors and car speakers are like night and day