There are two types of sound systems: integrated and layered. In an integrated combination sound system, all parts of its circuits (including the phonograph) are housed in a single casing, which is generally used in low-end combination sound systems. In a layered combination sound system, the number of layers divided varies depending on the grade of the machine. Among the multiple layered combination audio systems, there are: one layer for record players, one layer for CD players, one layer for tuners, one layer for dual card recording and playback stands, one layer for tone controllers, and one layer for main power amplifiers. In a combination sound system with fewer layers, the jukebox and CD player each have one layer, while the others have one layer. Miniaturization, digitization, specialization, and film and television are inevitable trends in the development of home audio.