THX Loudness Plus is a volume control technology featured in THX Certified Dominus, THX Certified Ultra and THX Certified Select Certified AV Receivers, preamplifiers and amplifiers that automatically adjusts the front-to-back speaker level relationship as you turn the volume down. With THX Loudness Plus, audiences can now experience the rich details of surround sound at any volume level. All movies, music, and games are mixed at Reference Level in the studio, to be played back at the same Reference Level in the cinema or home theater (0 db on the volume dial for THX Certified Receivers is equal to the studio Reference Level). However, many of us find the Reference Level is too loud for our homes. But, turning the volume down often means that elements of movie, music and other soundtracks are lost or perceived differently from the original sound mix. THX Loudness Plus maintains the integrity of soundtracks when listening below Reference Level. The technology compensates for the tonal and spatial shifts that occur when the volume level is reduced. By automatically raising the levels of the ambient sound, you experience the true impact of movies, music, and games regardless of the volume setting.