2.1: The Magic Number
If you start with the premise that a computer speaker system should take up as little room as possible but still should be able to restore the entire sound spectrum, there is really only one solution: one pair of small speakers and one large subwoofer for low frequency sound. This is what the 2.1 system is about: two satellites and a subwoofer that houses many key electronic components, such as the power amplifier. The subwoofer also has the mains power input, which can be integrated. This approach helps to reduce the size of the satellites, which do not need to turn out very low frequencies. The inevitably bulky subwoofer can also be tidied away out of sight under a desk without any adverse effects on sound quality.
This kind of system has to be at least bi-amplified (one channel for the subwoofer and one for the satellites). An electronic filter prevents frequencies from reaching the speakers that are not supposed to receive them. Filtering between the satellite speakers is usually passive but is sometimes bi-amplified. This attribute is arguably superfluous for this sort of equipment.
It rather looks as though our three contestants consulted each other over the design of their satellites. The idea seems to have been to make them as slim as possible so they would fit neatly beside the monitor. The trouble with this idea is that it is not compatible with quality sound reproduction and, as we shall see, it has resulted in convoluted solutions.
Regarding the subwoofer, obviously loudspeaker size, enclosure volume, response range and the highest possible sound level all have to be fielded and the ideal compromise is not easy to find! But in any case, it is better for it to have a separate and accessible sound control system because, depending on the position and the music played, the best levels can differ quite a lot.