An electronic system that plays an audio source over loudspeakers. It comprises source components (CD player, FM tuner, etc.), an amplifier (amp) and speakers. The amp boosts the signal to drive the speakers, and it contains a preamplifier (preamp) that switches between input sources. The preamp also provides an equalization circuit for phonograph records (see
phono preamp). In most stereo systems, the preamp and amp, along with an FM tuner, are packaged in one unit (see
stereo receiver). In high-end systems, the preamp, amp and all audio sources are separate components.