2 speakers system: cheap and medium quality, the lack of subwoofer limits the quality of the sound.
The 2.1: 2 speakers and 1 subwoofer, some of these systems are of excellent quality, wide range of prices.
The 4.1: 4 speakers and 1 subwoofer for spacial sound around you. System recommended for 3D video games to better identify the enemy in space.
5.1: 1 additional center speaker. Designed for watching DVD today mostly encoded in 5.1.
Make your choice based on your needs, no need to opt for the 4.1 or 5.1 if you do not watch movies or do not play on your computer. Remember also to congestion.
The quality of the sound
Operating frequencies higher the frequency range is wide, most speakers are able to return a broad spectrum of sound, more serious most acute. Check especially the quality of the subwoofer that restores the low frequencies. The human ear perceives frequencies ranging from about 20-25 Hz to 18-20 kHz. Choose speakers who have frequency ranges close.
There are labels of private labels as the THX label, which may refer to your choice of quality speakers. Warning, these qualifications are not official.
Testing The best way to evaluate the sound quality is of course to listen to the speakers delivered. It is not always possible to store much less online.
Read advice you can give a first approach.
It is measured in Watts. Among the various types of Watts, the Watt RMS to be taken into account. The unit measures the quality, diameter and the number of speakers. Typically 10 to 70 Watts RMS.
Do not deduct more than the Watt RMS, the greater the PC speaker is quality. The power and quality are two independent features. It is better to have less powerful speaker but that does not buzz.
Pc-Connection systems for pregnant 2 speakers and 2.1, an analog stereo enough. For systems 4.1, 5.1, you'll need a digital input in S / PDIF.
Inter-connection elements constituting the speakers are connected by various cables. There are ways to connect without son, but only for pregnant 5.1.
To control the volume and bass without using your computer, some speakers have remote.