Virtual surround sound describes the process by which a surround-like effect is created from fewer than five speakers. So, instead of the 5.1, 6.1, or 7.1 system that's required for true surround sound, a virtual surround system requires only two speakers--possibly just one--plus a subwoofer for the bass. As a result of the speaker configurations, the virtual surround (or faux surround) systems are often called 2.1 or 1.1 systems. Bose was one of the first companies to popularize the 2.1 format with its 3-2-1 systems, but several other manufacturers--including Yamaha, Niro, and SoundMatters--have since joined the fray.
Some virtual surround systems are all-in-one home theater packages (HTIBs) that include the speakers, an amplifier, and a DVD player. Others require you to supply your own DVD player, but they include built-in surround processing, so there's no need for a separate amplifier. Others systems are just speakers and need to be connected to an A/V receiver.
The big advantage of virtual surround systems is what they lack. Fewer speakers means fewer wires, less complexity, and easier setup. And there's an obvious aesthetic advantage: Not only are there no speaker cables stretching to the back of the room, there aren't even any speakers back there. Instead, you're getting all of the room's audio from just one or two speakers--usually set up to flank a flat-panel TV.
But there's always a catch. While the better virtual surround systems can produce a palpable surround effect, we've never heard one that completely duplicates a true 5.1 system; it's especially hard to re-create rear channels. Also, because many of the systems reflect sound off walls, they may not work well in rooms that aren't perfectly rectangular, are too big or too small, or are densely packed with furniture. Moreover, many virtual systems work best in a focused sweet spot--say, the center of the sofa--and if you're sitting outside of it, you won't benefit from the surround-like sonics.
Because of the drawbacks, die-hard home theater purists will probably eschew virtual surround setups. But for those who prefer a home audio system that blends into the background instead of being the center of attention, virtual surround systems are a great option. Also, even those enthusiasts who have a dedicated home theater in one room of the house may find a virtual system is a worthwhile choice for a secondary room, such as a bedroom or a den, where space is at a premium.