Okay so im putting in a new system in my car and i need to know if there is a reason to buy a crossover and put one in. Ive been told that this crossover is pretty good http://www.sonicelectronix.com/item_8160_AudioControl+6XS+-GRAY-.html.

What is the purpose of having a crossover like this?

Any help will help. Thanks

An external crossover really isn't necessary in most basic systems. Back when products like that Audiocontrol came out, a lot of amps didn't have any built in crossovers. Anymore a lot of products you will have installed already have crossovers built in; i.e. headunits and amplifiers. Unless you were planning to get a little more advanced and run "active" (do a search if you don't know what that is), an external crossover isn't necessary.

Even then, that Audiocontrol piece is archaic and outdated. Not worth $220, and not worth purchasing compared to other products available on the market.