A basic Home Theater setup consists of a monitor (CRT, Plasma, or LCD), A/V receiver, and speakers. The number of speakers used is determined by what level of surround sound you wish to achieve. In most cases you have a Center speaker, Front left and right speakers, Surround left and right speakers, and a Sub-Woofer. Along with a capable A/V Receiver and audio source (DVD player, Satellite Receiver, or Cable Box) you can hear Dolby Digital 5.1 sound. In order to hear 6.1 or 7.1 surround formats you need either 1 or 2 additional speakers located in the rear.