A 2-channel amp will power two speakers (or a subwoofer); a 4 channel-amp provides a few more wiring options.

Which amp is right for me?

As a rule, there's no reason to buy more amplifier power than you need, and this is especially true with factory stereos and speakers. A monstrous 1600-watt, 4-channel amp will simply overpower your factory system.

Most factory receivers do not put out a lot of power — 8-10 watts RMS would be considered average. As a rule of thumb, you'll need to increase your amplifier power by a factor of 10 to double the volume level. So if you want the volume to be twice as loud as it is now, you'll need an 100-watt per channel amplifier (keep in mind that factory speakers won't handle this kind of power). However, even a relatively small outboard amp (with as little as 25 watts RMS per channel) will produce a noticeable increase in the clarity and impact of your speakers.

If you just want to power two speakers (or a subwoofer), choose a 2-channel amp. A 4-channel amp will drive four speakers, two subwoofers, or two speakers and a subwoofer (a common configuration, particularly with rear speakers for additional "fill").

Amplifier placement will depend on whether you are powering front and/or rear speakers, or a subwoofer, as well as the cargo space in your vehicle.

Check out our Learning Center articles for tips on choosing the right amplifier for your vehicle.