Pretty sure the filters are just for PCM conversion as the manual states
When selecting NDSD DSD setting, the DSD post noise filtering is done in the analog domain so there are no DSD filter settings. An artifact of DSD processing is the buildup of ultrasonic noise and with DSD 64; this noise starts at 24 kHz and rises to peak level at -50 dB at 50k and beyond. In the M3 set to NDSD DSD this filter is implemented with a simple low order low pass analog filter for the very best sonic performance