Adafruit stereo 28w class d audio amplifier i2c control agc adafruit 1552 the adafruit stereo 28w class d audio amplifier features agc automatic gain control and up to 89 efficiency making it ideal for battery powered projects an onboard mini dip switch lets you control the gain quickly and easily though it can be controlled by signals from off the board theres also a shutdown pin for each channel 10microf capacitors on the input channels make them fully differential the r and l