The MM-4x and C-4x enclosures are constructed of extremely rigid fiber-reinforced polymer matrix composite, and the non-square sidewalls of the enclosures help to increase the overall sound quality. The S-8 and S-10 powered subwoofers are made from ¾-inch Medium Density Fiberboard (MDF) to withstand the pressures and vibrations of strong bass at loud volumes. Unlike value-oriented “mini-systems”, RBH Sound uses special aluminum cone woofers for the highest possible performance from these smaller speakers and subwoofers. RBH Sound’s CTx Series makes it easy to upgrade from a standard 5.1 system. Newer surround sound formats seem to come out all the time, and typically require more than just 5 speakers and a subwoofer. Just by adding another pair of MM-4x speakers, you can easily upgrade to a 7.1 system and immediately enjoy the sonic benefits of a totally integrated and matched eight-speaker system. Designed to provide the finest quality surround sound experience, the RBH Sound CTx Series is among the best-of-the-best in smaller home theater systems.