Yamaha AV-55 is a four-channel power amplifier, capable of driving a pair of rear and a pair of front speakers. It can be connected to a control amplifier, surround-sound processor, or other audio devices via its input terminals. The amplifier also features an unswitched AC outlet, which can be used to power another audio component.

With its 2-/4-channel selector, the Yamaha AV-55 can be used for both two-channel and four-channel operation. In two-channel operation, the speaker level controls can be used to adjust the volume of the sound reproduced through the left and right speaker systems. In four-channel operation, the controls can be used to adjust the volume of the sound reproduced through the front and rear speaker systems.