A Preamplifier is a device in which the user can connect all audio or audio/video source components (such as CD or DVD players). The preamplifier then can switch between sources, process audio and, or video, but also supplies an output signal to what is referred to as a Power Amplifier. The Power Amplifier then supplies the signal and power needed to the loudspeakers.
When a preamplifier and power amplifier are combined in one unit, it is referred to as an Integrated Amplifier. In addition, if the Integrated Amplifier also includes a radio tuner (AM/FM and/or Satellite Radio) then it is referred to as a Receiver.