New Main board being drawn up ! ADC DSP ARM DAC !

I will be using stm32f7xx to multichannel record/playback TDM8 to DSP

I should be putting the ADC and DAC onto a daughter card so I can change the IC's later but NO , I've already started

routing it now :) so far its about 10cm x 6cm and might be able to get smaller since i finally started using 0603 parts.

I'm not sure it can get any smaller because of heat ! There is fair amount going on here :)

Its a 4 layer board with partitioned ground analogue and digital ground plane.

i'll be using a 40 pin IDE cable to hook up the analouge IO and 5v power to the Preamp and driver board.

why ? because they are everywhere for free :)

I'm not really convinced I should be running the 3.3v LDO for the digital stuff ( DSP and ARM ) off the analogue +5v rail !

perhaps that could add noise to the analouge +5v rail on the preAmps ? anyone have any thoughts on that ?

Will the LDO put noise onto its input ? can I isolate this without transformers? or should I really have a whole other

channel to make the digital power?