Factory sound processors take your factory stereo's signal, clean it up, and send a corrected audio signal to your aftermarket amps and subwoofers.

Your car can be a great place for music listening. Many commuters suffer for hours each day with inferior sound quality that they'd never tolerate from their systems at home. Here are some tips on how to improve sound quality in your vehicle, whether you're listening on a simple factory system or a multi-channel amplified setup.

Just because you can't replace your vehicle's factory stereo doesn't mean you have to live with a poor sound system. In this short video, Crutchfield experts take a look at how a fellow employee created a high-performance car audio system.

The JBL MS-2 is a portable digital signal processor that improves the sound in your car when you use a portable player like an iPod. It does not require permanent installation, so you can take it from car to car. It'll clean up your factory sound, even "premium" amplified systems. And it also works with aftermarket systems, including those with subs.

Part 3 of our series: Jeff upgraded his speakers again, ran higher-quality wire, and added a processor to sculpt the sound. He had to modify his door a little to get the speakers to fit — but when you want the best, there's no need to let a little modification get in the way.

Factory stereo systems leave a lot to be desired. This problem now has some solutions that let you keep your factory stereo and get spectacular sound, customized for your specific vehicle. The four upgrade systems we discuss in this article improve the factory sound of different vehicles in different ways.

A Rockford Fosgate system gave the family minivan a major audio overhaul while still keeping the manufacturer's dual DVD players intact for the kids.