For amps that need audio attenuation, this FSR™ Line Level Volume Control Module provides a fast, easy way to connect a control system to an existing audio system and gain simple control. It features all the connections you need to ramp the audio of any line level signal, plus it supports both pro level and consumer level audio for maximum application flexibility. 
FSR™ Line Level Volume Control Module
For amps that need audio attenuation, this FSR™ Line Level Volume Control Module provides a fast, easy way to connect a control system to an existing audio system and gain simple control. It features all the connections you need to ramp the audio of any line level signal, plus it supports both pro level and consumer level audio for maximum application flexibility.
Important Note - This unit does not include a 12VDC power supply. You can use EE-PS-12VDC-1A as an alternative. 
Complete Control
Equipped with RS-232, Relay, and Potentiometer control options, this unit can easily integrate with any control system on the market. It features attenuation from 0 to -62dB with 1dB steps, ramp holding, and direct muting. This module also features a serial loop out for controlling multiple units with one serial connection.
Line Level Controls
This control module can be set to compensate for either Pro level audio or Consumer level audio in both balanced and unbalanced configurations –providing a +12dB boost on Consumer level (a 4X volume output). Plus it can be set to combine unbalanced stereo L/R audio into a balanced mono channel.
LED Indicators
Programming and testing this volume control module is easy, thanks to its handy LED indicators. They show you what’s happening with the unit, so you can see which serial commands have been received and are functioning properly – and if the volume is muted.