The ET2354 is a 4 stereo inputs/2-channel outputs digital control audio processor for the low voltage operation. Volume, tone(bass and treble), and balance(left/right) processor are incorporated into a single chip. The ET2354 also has the loudness function and selectable input gain. These functions can be built a Hi-Fi audio system easily. All functions are programmable via the serial I2C bus. The default states of the chip as the power is on are: the volume is -78.75dB, the stereo 4 is selected, all the speakers are mute and the gains of the input stage, the bass and the treble are 0dB.