In a perfect world, you'd have room in your home theater for eight separate speakers (including the subwoofer), and you'd have all of your speaker cables neatly hidden inside the walls. In other words, you'd have a butt-kicking but aesthetically pleasing 7.1-channel surround sound system.
Sometimes, however, reality intrudes upon your perfect home theater world. Some folks just don't have the room for a full surround sound setup, or they have issues with the layout or construction of their room that keeps them from installing the full complement of surround sound speakers.
Many folks in this predicament are forced to stick with two-channel (stereo) audio and thus forgo surround sound. You do have an alternative though - several manufacturers produce virtual surround sound speaker systems that incorporate multiple speaker drivers and some fancy electronics in a single speaker unit, which you place in the front of the room (usually right above or below your display).
These virtual systems use a combination of physical "aiming" and electronic trickery to introduce timing delays in the sound coming out of the speakers' drivers, which makes the sound "bounce" off your walls in a coordinated fashion. The result - although typically not as "immersive" as a full set of surround speakers - can come a lot closer to real surround sound than a pair of stereo speakers can.
One example of these virtual systems is the Yamaha YSP-800. This system replaces not only all of your speakers, but also takes over the job of the A/V receiver. Connect your audio and video sources (such as a DVD player) into the back of the YSP-800, plug it into the wall, and (with a little setup) you have convincing surround sound from a single speaker. It's a great setup for a quick and easy surround sound system for a smaller room or an apartment home theater.
