This is weird: the Hifiberry image should automatically detect the correct board. Do you really have the DAC+ Pro – or the Digi+ board?
If it is the first: change it to
dtoverlay=hifiberry-dacplus
And reboot.
I know the case (have it myself) and agree it’s hard to do anything wrong with it. Still, it won’t hurt to check.
If all else fails, you may want to try the DietPi route. It has a few advantages (optimised setup, loggin to RAM instead of SD) and is way easier to troubleshoot. More info here (long thread alert):
