So I am starting to work through all designs again. Specifically looking to rationalize the power supply regulators and reset circuits across all boards. And also to look for cheaper parts where possible.
The ADAU1966 DAC PCB may have an issues with the reset circuit. I used a 2.5V reset circuit (as the 2.5V rail is critical) which feeds the 2.5V output to the ADAU1966 reset pin. On several boards I have this works fine. The "trip" point should be 2.3V so some margin. However I have one ADAU1966 that is being a little fussy.
Some hindsight would have been good as a couple of transistors would have pulled the reset pin up to 3.3V. However now would seem like a good time to look for some cheaper/more universal reset supervisors (with open-drain outputs).
An electronics engineer and a long term electronics hobbyist. I like tinkering with stuff and making things.