The SSM2160 allows digital control of volume of six audio channels, with a master level control and individual channel controls. Low distortion VCAs (voltage controlled amplifiers) are used in the signal path. By using controlled rate-of-change drive to the VCAs, the "clicking" associated with switched resistive networks is eliminated in the master control. Each channel is controlled by a dedicated 5-bit DAC providing 32 levels of gain. A master 7-bit DAC feeds every control port giving 128 levels of attenuation. Step sizes are nominally 1 dB and can be changed by external resistors. Channel balance is maintained over the entire master control range. Upon power-up, all outputs are automatically muted. A 3-wire or 4-wire serial data bus enables interfacing with most popular microcontrollers. Windows software and an evaluation board for controlling the SSM2160 are available. The SSM2160 can be operated from single supplies of +10 V to +20 V or dual supplies from 5 V to 10 V. An on-chip reference provides the correct analog common voltage for single-supply applications. The SSM2160 comes in a SOIC package; see the Ordering Guide for details.