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.

Stereo sound at its simplest means that two microphones are used for a recording, each picking up a slightly different signal. When these two signals are used to power separate loudspeakers, your ear detects a subtle difference in the sound; the effect on the ears is like that of 3D cinema on the eyes.