Use the following guidelines when selecting computer speakers or headphones:
Picking suitable speakers requires considering what you listen to, how you listen to it, and the features of your audio adapter. For example, if you listen mostly to classical music at low to moderate volume, powerful bass is less important than flat, transparent frequency response in the midrange and highs. A high-quality set of dual speakers with frequency response from 90 to 18,000 Hz and 4 or 5 watts RMS per channel will serve. Conversely, if you listen to rock or heavy metal, or if you play games and want to shake the walls, crystalline highs are less important, but bass is critical. You'll want speakers that include a powerful subwoofer. Similarly, if you have a 3D audio adapter, it makes little sense to couple it to a two-piece or three-piece speaker set. Buy a speaker set with enough speakers to take advantage of the 3D positional audio capabilities of the card.
The very cheapest speakers, those that sell for $5 or $8 or are bundled with inexpensive PCs, have sound quality noticeably inferior to speakers that sell for even a little more. Speakers in the $15 range and above use better (and more powerful) amplifiers, better-quality drivers (typically separate midrange/woofers and tweeters), and provide additional features, such as the ability to connect more than one sound source or a separate subwoofer.
Altec-Lansing, Creative Labs, Labtec, and Logitech are the best-known names in inexpensive computer speakers. Each produces a broad range of speaker models, one of which should be appropriate for almost anyone. Increasingly, well-known names in home audio such as Bose, JBL, Klipsch, and Polk Audio are entering the computer speaker market. Ironically, their background in high-quality home audio means that they tend to publish realistic specifications for their computer speakers, which make them look inferior to lesser speakers for which the makers publish inflated specifications.
Most computer speakers use an analog audio interface, which allows them to connect directly to the Line-out jack of your sound adapter. Some computer speakers particularly high-end four-, five-, and six-speaker sets instead use a direct digital connection via a Digital DIN connector, an S/PDIF connector, or both. If you are using a traditional sound adapter, make sure that your sound adapter and speakers share a common interface method.
Even inexpensive headphones often provide a better listening experience than good computer speakers, both because the cushions isolate you from ambient noise and because it's easier to render very high fidelity sound with the small speakers and tiny power levels used by headphones. Headphones also allow you to work (or play) without disturbing others. If you're going to buy headphones, consider instead buying a headset, which adds a microphone to support such functions as voice/speech recognition, VoIP telephony, and adding voice annotations to documents. The only drawback to headphones is that most are not well suited for use with 3D audio adapters, although some specialized four-channel headphones are available.
With speakers more so than any other computer component except perhaps input devices, personal preference must rule. Speakers that sound great to us may sound mediocre to you, and vice versa. The only way to know for sure is to listen to the speakers in your own environment. If they turn out to be unsuitable, you don't want to be stuck with them, so make sure you can return them without a hassle.