So, I got it limping along, but with issues…
Since the U/I does not know about the overlay for hifiberry-dacplusadcpro.dtbo, I went in and instantiated a copy of DAC+ADC, calling it DAC+ADC Pro, in /var/www/max2play/application/plugins/hifiberry/controller/Setup.php, and having it configure the dtoverlay to hifiberry-dacplusadcpro. Verified that config.txt was set to the appropriate driver, added some amixer settings to override input defaults (input selection, gains, turn off mic bias, etc.) rebooted and the interfaces came up as expected. I also did an apt update and upgrade to ensure I had the latest (along with all the other patches and security upgrades that have been neglected up to this point).
With this, card Input works as expected, the input LED comes on, audio is captured, and I can fine-adjust input gains with alsamixer.
Now, what is happening, is nominally every 90sec (varies from 2sec to 2min) I get a single sample full-scale ‚POP‘ at random on either the right or left channel (never both at the same time). I’ve cross-posted this issue with Hifiberry as well. Since it is a single-sample, the tweeters are the only speaker taking the hit. I’ve since switched back to the DAC+PRO driver and the popping is gone, but input is not working either.
Thanks
UPDATE: Chatting with the Hifiberry folks, the principal difference between DAC+ADC and DAC+ADC PRO has to do with clocking. Apparently the PRO model uses an internal clock, so the RPi must slave from this clock. I do not yet know if this difference applies to DAC+PRO and DAC+ADC PRO.
CORRECTION and confirmation from Hifiberry: DAC+ADC uses the RPi clock. DAC+ADC PRO uses a clock generated on the hat.
