Ok thanks for your feedback.
To start with the ‘bad’ news: the reason your DAC is not supporting native DSD is because it does not provide a so-called altset. Which is rather strange, as indeed your DAC is equipped with the Amanero chipset that does actually do this.
The only thing I can imagine is that your DAC is not equipped with the latest firmware from Amanero; their earlier firmware was indeed not capable of doing native DSD on Linux. So it might be good to contact them.