I don’t give up easy on these types of problems 😉
The problem is certainly not with your hardware. That is why I am looking at the recording and/or the effect of DPS on the recording. Let me know when you try the -3dB Paris profiles.
So I think if I am to have insight into the issue I need to hear a recording of the distortion.
Has anyone else on this forum had distortion issues with a DAC?