I already know that a library is causing my problems. But now I don't know how to fix it, because I was trying so many things.
As you already stated in that thread, something did mess up the GPIOs. https://support.hifiberry.com/hc/en-us/community/posts/360005269057-Using-HiFiBerry-DAC-with-MCP3008-makes-the-audio-device-get-stuck
But how do I find the culprit so that I can nuke it? And how do I check the GPIO settings and what should it be?
I really want to use the AMP2 it looks like a great solution for my setup.