If you are up to an inexpensive experiment I'd like to get your feedback. Scrounging the forums Ted Smith (the designer of the PSAudio PerfectWave DAC) suggested that the issue with USB as a connection is the 5V power included within the signal cable. His suggestion was to insert a linear powered USB hub to clean up the signal. I haven't purchased the 5V linear power supply yet but just blocking the power from the computer and using a powered hub I was able to make a significant change to my system.
Power blocker to remove the 5V from the source
https://www.amazon.com/dp/B094FYL9QT?psc=1&ref=ppx_yo2ov_dt_b_product_details
Powered USB 2.0 hub.
https://www.amazon.com/dp/B000T9S4CI?psc=1&ref=ppx_yo2ov_dt_b_product_details
So for about $30 I was able to improve separation and add low base.
Both items are returnable if your experience isn't positive but I've got to get my head around the changes before I spend the additional $90 for a LPS.
Cheers