If you've decided to buy an amp for your mobile sound system, you've made a smart move. Whether you'll use your amp for boosting the power to your full-range speakers, or for powering subwoofers, an amplifier will make a big difference in your system's performance.

Your first step, of course, is to decide how powerful an amp you need. If you're uncertain about that, take a few minutes and check out the article on Powering Your Subwoofer for Peak Performance, as well as Todd Cabell's article Matching Car Speakers to Your Mobile A/V System for some valuable insights on what you'll need. Once you've decided on the basics, you'll need to decide which amp to purchase. With the number of choices available, deciding which one to buy can leave you scratching your head. You may find that there are several amps available that have the features and specs you're looking for, and the only difference you can see is the price.

If you're choosing between two similarly featured amps with a big price difference, is there a benefit in purchasing the more expensive model? Does it really matter which amp you pick?

To start answering these questions, let's first take a look at how amps work.

Understanding the fundamentals
Very simply described, there are three parts to a power amplifier. The preamp section is where the signal comes into the amp, and where devices like crossovers and equalizers are located. The power supply provides the energy to power the amplifier, where the signal boosting output transistors are located.

This very basic amp diagram shows the three main sections of an audio amp.

The quality and layout of the components in each part of an amplifier are crucial in determining how well the amp performs. A well-engineered and designed audio amplifier will have clean, uncluttered circuit boards, with all the elements carefully and logically laid out.

The power supply of the amplifier will do a better job of providing supplies of clean power if it has heavy-duty capacitors. This will ensure that there are adequate reserves of power available when you're bumping your tunes up to high volume.

In the amplifier section, powerful output transistors are essential to feed clean output to the speakers. It's very important that the output transistors have an effective way to dissipate the heat that is the byproduct of the amplification process. This will give you the cleanest possible sound.