This Module is currently available.
3 Digitally Controlled Analog Attenuators
The Digital Attenuators module is 3 digitally-controlled analogue attenuators (use them as VCAs) with a multipurpose sidechain input and switchable AC/DC coupling in 1MU. Each cell is built around a microcontroller and a digital potentiometer (an IC which functions as a digitally-controlled resistor pair, essentially), because only the digital potentiometer and unity i/o buffers are in the signal chain this is an extremely clean VCA.
A benefit of this arrangement is being able to read the audio input into the microprocessor and only update the digital potentiometer at the zero crossings of the input signal. no more irritating clicks on sine wave bass! in addition, the sidechain input can be used to send a different signal for reference to the zero crossing detector, which can also be switched to look for triggers or switched off completely so the digital potentiometer is updated constantly.
These merchants probably sell this module. Huh?