OK. It works!
Not sure how much of my fiddling was necessary, yet, but I have stereo AUX-out with Volume control, which is all I’m looking for.
Without regurgitating everything I tried various things in this thread IQaudiO Pi Digi+ helped.
In config.tx hashed out dtpram
#dtparam=audio=on
Edited the dacs.json file adding this line
{“id”:“iqaudio-codeczero”,“name”:“IQaudIO Pi-Codec Zero”,“overlay”:“iqaudio-codec”,“alsanum”:“2”,“alsacard”:“IQaudIOCODEC”,“mixer”:“Digital”,“modules”:“”,“script”:“iqamp-unmute.sh”,“needsreboot”:“yes”},
Added a new codec state file in the boot directory. I created codeczero.state and pasted in Github playback only files
I then ran this as appropriate
sudo alsactl restore -f filename.state
which loaded the file. Which will be temporary at this point.
Testing Volumio, I still got the ALSA No such device “Volumio” error. However, If I turned off the I2S DAC, I then got this…
Which is not quite right, but it works!
Now to reboot, and see what breaks. I’m not convinced by the dacs.json file either as its come up with IQaudioCODEC not IQaudIO Pi-Codec Zero which I was expecting…
I also need a suitable enclosure, as the one I bought is almost, but not quite big enough. Typical!
-------UPDATE-------
I think the correct Dacs.json file above will fix it. Im not convinced the state file made difference. I need to do another fresh install to try at some point.