According to the ADI-2 DAC’s manual, this is a limitation of certain Windows configurations.
Might have been overcome lately, Windows is a moving target.
If it works and sounds right ...
ADI-2 DAC’s manual, page 34:
...A DSD playback via USB (State Overview shows DSD) will be done at 176.4/192 kHz for DSD64, 352.8/384 kHz for DSD128, and 705.6/768 kHz for DSD256. Under Windows WDM/WASAPI are currently limited to 384 kHz. The highest sample rates and DSD modes can only be used via ASIO. RME’s driver supports DSD over ASIO in DoP format as well as ASIO native. ADI-2 DAC therefore is compatible to many programs, ...