Please try setting Roon DSP Engine to upsample everything to DSD256 and see if it works with your setup using DoP. From my standpoint, whether you can play DSD256 is far more important than having native DSD.
Alternatively, instead of upsampling, you may also try the Stereo DSD256 files here:
This is an example of Lumin Luxman D-03X combo playing DSD256: