I just bought probably my 5th or 6th HiFiBerry device. Really enjoy them.
Just got the Pi Zero Mini Amp in the mail today and tried to configure it only to find out that there doesn't seem to be any instructions on the site anywhere.
I presumed I would add
dtoverlay=hifiberry-amp (based on the config for Amp / Amp+)
That got me no devices when I did
Just messing around I then changed it to
which indeed worked. Hooked it up to a set of speakers and it works like a champ, sounds pretty good, and gets a little louder than I thought it might.
Anyway I recommend that some configuration directions be placed in the knowledge base.
New Bern, NC