I've got a Digi2 Pro and found no way to make it work, tried with 2 different RPi4's. I've tried both coax and optical outputs to no avail. Nothing else is connected to the pi.
With HifiberryOS, the sound card seems to be recognized in the WebUI - it shows 'Digi2 Pro' under General-System tools-Diagnostics- System info. However no sound can be played.
Even if I try to edit it, after each reboot the dtoverlay in config.txt will be rewritten to 'hifiberry-dac'.
aplay -l gives me:
**** List of PLAYBACK Hardware Devices ****
card 0: sndrpihifiberry [snd_rpi_hifiberry_dac], device 0: HifiBerry DAC HiFi pcm5102a-hifi-0 [HifiBerry DAC HiFi pcm5102a-hifi-0]
Subdevice #0: subdevice #0
Can someone confirm whether this is a defective piece of hardware?