Just wanted to report back that I changed up the streamer. I received the Digione last night and provisioned an RPI4 w/ volumio. My first impression - I'm astonished that it made such a difference. In the few tracks I played to test, the almost unlistenable glare is gone. It's still a ways from the analog detail and warmth that I'm after, but this was a significant step toward that end. I can't imagine what an upgraded DAC will bring.
The best part is that its portable - so I also tried it with my Bottlehead Crack w/ (budget) Toneboard DAC. Bingo -- at the very least much quieter background (in addition to the Digione, improvements could also be attributed to using SPIDF on DAC instead the dual data/power setup that I had via USB).
Overall, I'm impressed to say the least. I'm going to let this setup burn-in for a while and really listen to it. Much appreciate the recommendations!
Next upgrade with be to an Orchid MHDT or Border Patrol DAC