in the glossary at circuit city website the definition to THX is : THX - Lucasfilm Inc. has developed a certification process for audio and video components that meet their high standards for home theater performance. THX-certified components incorporate specific performance features and circuits designed to compliment and enhance other types of surround sound systems, like Dolby® ProLogic and Dolby® Digital. I noticed that only the more expensive home theater recievers offer THX. Is it worth paying top dollar to have this THX? What is it all about? THanX !!