Clean implementation of stepped volume control / attenuator

I am looking for a clean implementation of a stepped volume control (attenuator) that can be controlled from the Volumio volume control.

The quick and easy answer would be to use the Allo Relay Attenuator with it’s Volumio plugin. While functional, the Allo attenuator is designed such that the digital/microcontroller GND is connected to the audio signal GND. The digital side may inject noise into the clean audio GND, and the two GND connections to the board (audio and digital) cause ground loops. Not good.

There are a number of well designed relay controlled stepped attenuators out there. However, I have no clue what is required to control them with Volumio, and how to implement this in a plugin. Can someone point me in the right direction?