For DSD music, it's usually best to turn off Ultrasonic Filter for DSD, and not to convert it to PCM. This applies to both Lumin app and Roon playback.
For Lumin app playback: For 44.1kHz PCM music, you can experiment with whether leaving it as native 44.1kHz, or changing it to 176.4kHz (with output bitdepth set to 24) or DSD makes it sound better. Test with different types of music.
For Roon playback: Experiment with DSP engine to convert PCM music to DSD64. See if you like it or not. Test with different types of music.