Obviously you are way past where I ever got with PC sound. Once I got my first streamer (of 6 current) ones I pretty much abandoned it except for ripping/mastering. I did notice quite an improvement in minimizing PC noise using Fidelizer. I recommend trying the free version. He even responds to tech requests.
I think for your purposes and desires you would be be better off springing for Audiovarna (but I have never tried it.) I have an E50 on my PC, replacing a Schiit multibit that failed and they refused to repair. I love it. I do much of my listening through a second one (my first) in my media room. They are currently $169.15 making me tempted to buy a spare. I use one (on the PC) in DAC mode and the other in pre amp mode. They are both wonderful.
Please allow a few observations from a cranky old man:
Paul at PS Audio records exclusively in DSD at his Octave Records studio. He insists that there is zero loss in SQ by playing them back in DoP mode. Before I read that I felt like you, but I have noticed no difference. All my DSD files are .dsf. You could try that.
Good luck wherever you find it, you sound like a serious practitioner of audio art. Sorry I cannot be more help but I too have found foobar to be somewhat difficult. I can’t recall ever playing DSD on my PC but now I have lost interest in that.
Peace be with you.