Designmaster from Groupdiy sent me an interesting PM regarding my Power Distribution plans.
"How do you want to make the 5V for the ADC. For example the PCM4202 needs 65mA for the 5V analog voltage. You have 18V going to the board.
This will result in over 0.8W of dissipation loss and will generate heat which is not the best for thermal noise performance. I would recommend an additional supply rail with lets say more than 5V for the ADC or DAC may be 7V than you have the option to use a 5V voltage regulator on the board and than you will get a nice and low-noise supply.
How about 48V for phantom powering if you plan to go for a MIC Input board with integrated ADC? "
That made me think a little further. My initial plan was to only have a single "Hard Drive" type power connector. However, I soon needed more connectors (5.. not 4... )
So, a little more thought, means that I could have a 4 way digital connector and a separate analog connector. It would also means that my supply boards can be completely separate on the board.