A surround amplifier is able to provide sound in surround quality as Dolby Digital. A stereo amplifier will as it say only provide stereo sound.

THX is the trade name of a high-fidelity sound reproduction system for theatrical movie theaters, screening rooms, home theaters, computer speakers, gaming consoles, and car audio systems. THX was developed by Tomlinson Holman at George Lucas's company Lucasfilm in 1983 to ensure that the soundtrack for the third Star Wars film, Return of the Jedi, would be accurately reproduced in the best venues.

Each THX Certified Product is engineered to perform best in specific room environments. Room size, acoustic design and system setup are all critical factors to how movies, music and games are experienced in the home.

THX Ultra2 Certified Products are engineered and designed for large home theaters. Viewing distance of approximately 12 feet / 4 meters from the display to the listening position.

Digital Theater Systems, a company which produces multichannel audio systems for cinema and home video, refers to an 6-channel audio system.

A 6-channel surround sound system developed by Dolby Laboratories. The audio is separated into front left, center, front right, rear left, rear right, and low frequency effects.