First the basics: What does an amplifier do, and do you really need one? In a nutshell, a stereo amplifier receives a low voltage signal from the source equipment — a CD player, Blu-ray DVD player or turntable, for instance — and enlarges or amplifies it, sending the signal on its way to powering your speakers. The functions of an audio amplifier can be split into two sectors or components. The first component is known as a preamplifier. It connects all the source devices, can be used to switch between those sources, processes audio or video signals, and sends it all to the second component: the power amplifier. A power amplifier does the heavy lifting, increasing the amplitude of the signal to drive the loads of your speakers. You can select these components as separate units. Or you can get them together in an integrated amplifier, which is a simpler, space-saving option. It also eliminates the necessity of matching the technical specs of the two components so they can work efficiently in tandem.
Another factor that should be considered when you're deciding which speaker amp is the best for you is the class of amplifier. The most common classes are A, AB and D class. Class designations measure how the amplifier handles the input signal to output signal path, factoring in power, efficiency and fidelity, to identify each class of amplifier's performance and characteristics. These designations get complicated fast, dealing with conduction angles, input cycles, sinusoidal wave conductions and more. But in a nutshell, a Class A amplifier gives you the best sound fidelity. But it is the least efficient of the bunch because it’s always on. A class A amplifier provides excellent sound reproduction, especially at low power, but this is at the cost of more energy used and more heat expended. This means adequate ventilation is mandatory. A Class AB amplifier maintains the sound excellence of a class A amplifier, but it adds more efficiency to the process. This makes it a popular choice for home theater and car stereos. A Class D amplifier is the most efficient amplifier type. It's often used in professional PA and car audio systems, where fidelity is of secondary importance to size, weight and heat dissipation.
Adding a new sound amplifier to your home audio system.
You prefer your volume loud. Your stereo is in a big room. Your speakers require a lot of power to drive. You love your bass response. These are all good reasons to add a sound amplifier to your system, even if you already have a receiver. As mentioned, amplifiers are capable of creating significant heat, so you shouldn't cram yours into a small, tight place. Plan on at least 3 inches of clearance above, plus space on the sides and back, to allow proper ventilation and to keep it from overheating. You'll also need room for the connections, the speaker wire and audio cables required to get everything hooked up. If you'd like, you can enlist Geek Squad® help for your home audio setup, which includes connecting your devices and setting up your speakers — all with optimal functionality and a professional look.