by Paul Sanders
The most important part of your stereo isn't the receiver: It's your speakers. If you plan on selecting your stereo speakers and audio receiver separately, you may want to learn more about a few speaker characteristics. When you know what to look for, you'll be able to assemble a speaker system with low distortion and detailed audio, even at high power levels. The most common points used to compare speakers are explained below.
Power: The specification to search for is the RMS (root mean square) power rating; it may be listed as nominal power or continuous power. The peak power rating on speakers lists the maximum power your stereo speakers can take without producing distortion. If you run speakers at peak power for an extended period, you won't get good sound quality and you may damage them. Match your speakers to a stereo receiver or amplifier that provides just a little more power than the RMS power rating of the speakers for the best sound quality with lower distortion at high volume.
Sensitivity: Speaker sensitivity is a measure in decibels (dB) of the efficiency with which your home speakers translate amplifier power into audio. Speakers with sensitivity over 90 dB or so will perform very well.
Impedance: Impedance is a speaker rating that's often misunderstood because it's an electrical concept that is somewhat counterintuitive. Impedance is a measure of electrical resistance and other factors in materials that conduct electricity. Speakers with lower impedance will put a heavier power drain on a home theater or stereo receiver. It's important to not connect speakers to a receiver or amp with lower impedance than the speakers are rated for. If you do, your amplifier or audio receiver may burn out.
THD: Total harmonic distortion (THD) measures a distortion of the sound produced by speaker systems. Lower THD means that your stereo speakers will produce a sound that's closer to the original audio source. THD is usually listed on speakers as a percentage of the total audio signal. You may start to notice audible distortion as THD approaches one percent. For better results, look for speaker systems with THD below 0.5 percent.