Version 3.11 Build 2. Rev 1396.
Added ADAU1372.dll to C:\Program Files\Analog Devices\SigmaStudio 3.11\. Started new project, dragged ADAU1372 device into workspace, made many changes under various tabs of "IC 1 - ADAU1372 Register Control", including under "Signal Routing" for "Output Select" "DAC 1": "Disabled". "DAC 0": "Input ASRC 0"
After hitting "Link Compile Download" and "Export System Files" I examined the contents of the "test_IC_1_REG.h" file and found it seeming to (at least prepare to) load value 0x1C to register (0x11) "DAC_Source_0_1" which seems to go against this giving the bits [7:4] in that register a 'reserved' value - I have always observed 'reserved' values as being a 'no-no' in this sort of thing.
On looking closer at the datasheet ( http://www.analog.com/media/en/technical-documentation/data-sheets/ADAU1372.pdf ), page 47, with regard to this register it seems worse when the reset value is defined as 0x10 in one place and then re-defined as 0x1 in another; further, between those two definitions appears similar;
7 6 5 4 3 2 1 0
which matches the first definition of the reset value but also happens to have one of the reserved values from the list in "Table 31" regarding "DAC_SOURCE1" using bits [7:4] - come to think of it, both these reset values put reserved values into both fields of this register,  &  are both listed as reserved there
What with DAC 1 disabled in every other regard I probably do not need to bother setting this source as disabled but, as SigmaStudio allowed me to when I checked this setting, what is actually valid here - is SigmaStudio 'right' that this is the 'disabled' value for that field or is my interpretation of the datasheet right that it is not possible to select other than 1 of the 2 input ASRC streams or is the third option I can think of correct?