This article is from the Car Audio FAQ, by Ian D. Bjorhovde (email@example.com) with numerous contributions by others.
Sound field processors (also known as DSPs) are fun toys to play with,
and can have some use, but it is generally good to keep the KISS
principle in mind: Keep It Simple, Stupid.
The fewer signal processors (this includes equalizers, and active
crossovers) that are in your system, the less chance there will be for
noise to enter your system. You'll also save money, have a lower noise
floor. Surround sound processors and bass regenerators are nothing
more than bells and whistles and are totally superfluous in a properly