A receiver consists of three main components: - Tuner. - Preamplifier. - Power amplifier. The preamp stage usually provides the input or source switching, tone adjustment, and a limited amount of signal amplification. The output of the preamplifier stage is internally connected to the input of the amplification stage, which amplifies the audio signal from the 1 to 2 VRMS range to a power level sufficient to drive the speakers. Access to the preamp output allows you to connect the line-level output of the preamplifier built into the receiver to one or more external power amplifiers. These may be used in place of the power amplifiers built into the receiver to provide more power to the speakers. Alternately, the preamp’s low-level output may be connected to power amplifiers and speakers located in another room. This can be preferable to running speaker wires to different rooms in a house, particularly if they are located on other floors or at the other end of the building. The preamp out may also be sent to an external sound processor whose output may be routed back into the receiver’s power amplifiers or to external power amplifiers.