I have tried both the standard and GUI versions of @Dan_Knight’s DietPi on the Sparky, but neither one show the Boss DAC as an option in soundcard settings. If I open roon and check the audio settings, I can see the Sparky device, but I only see “atm7059_link” (presumably the HDMI output) available to enable.
The green LED on the Boss is lit, so it seems to be getting power. However, it is not easy to make the physical connection. The supercapacitor on the Boss hits the heat sink of the Sparky before the GPIO connector is fully seated, so I have a foam bumper between them to keep them from shorting.
Do I need to install a driver to make it work? Or should I be using a different version of Linux? Or is the Allo.com website incorrect in stating that these two products are compatible?