I have adapted this logitech duet according to the site lampizator, there is also described how to do this (see link)
I also had a 12 volt linear powerboard myself that I adjusted a bit so that 9 volts comes out and that is exactly what the duet needs in terms of volts.
the raspberry pi has picoreplayer as software with a regular 5 volt power supply.
pay attention
Be careful with the removal of resistor R102 soldering from the XILINX, it will break if you solder it too hot and it will then be almost impossible to solder pin 3 to the XILINX.
the toslink output also no longer worked for me after the modification, I don’t know how this broke, maybe I hit something on the board.
by the way this duet streamer does not work with volumio, only with the volumio LMS (logitech media server) plugin and from there you can configure the duet.