The stock head unit in your car or truck has an amplifier built-in, so why replace it? Our guides to car amplifiers detail the reasons but the bottom line is, an aftermarket amp does a much better job. The aftermarket designers aren’t constrained by space so they don’t have to compromise on components. That results in clearer music with far less distortion, especially at higher volumes. And if you’re boosting your bass with a subwoofer an amplifier is essential. Without it the big speaker won’t get the power it needs. Our guide to the best car amplifiers to buy covers everything you need to know. We’ll explain what channels are and how many you need. We’ll bring you up to speed on power ratings and how to match an amp to your speakers. (You never want to skimp on watts, but you can have too much of a good thing.) We’ll delve into tricky subjects like impedance, which you do need to know about if you want to buy the best amplifier for your car. Head unit compatibility is another topic to consider. If you’re leaving the factory unit in place you should probably look for an amp with speaker level inputs. Alternatively, an aftermarket head unit will have pre-amp outputs that need line level inputs. Our amplifier guides take you through these points. A three or five channel amp could drive your subwoofer as well as your component speakers, but you might decide to give it it’s own amp. If that’s the case, take a look at our guide to the best mono subwoofer amplifiers. (Sometimes also called single channel amplifiers.) This guide covers the three classes of amplifier so you’ll learn why we prefer Class D. It even explains the role of CEA2006 certification, in case you’ve wondered what those markings mean. A good amplifier pays back it’s purchase price many times over by letting you hear your music more clearly. Read our car amplifier guides to understand the options and make the right choice.