My goal is to get higher frequencies like 65kHz out the analog pins using my my eval board.
Using your FAQ I can configure the SigmaStudio (and my AU1446) for 48k, 96k and 192k and at lower (audible) frequencies everything works fine on my oscope. Using the built-in sine generator I can generate and output 22kHz just fine, but >22kHz sines are wrong (output is aliasing). My ADAU1446 eval board uses an AD1938 for the analog output which seems to be a limiting factor and I can not configure it so it's stuck at 48k. The eval board's R14,15,16, 17 are open which disconnects it's communication from the iUSB.
SigmaStudio has a nice user interface for the AD193x part, is there a reason why this interface is physically disabled on the eval board? When adding the AD193x (I2C 0x8) to the Hardware Config I always lose connection the my ADAU1446. Is that because it's failing on the AD1938 or is there a conflict somewhere else?