Having listened to my system with the Ultra Fi Aubisque USB filter for a few days, I wanted to let you know that I am very happy with its performance.
It seems to work as advertised, significantly reducing noise and minimizing differences between USB cables and player software upstream of the Aubisque.
Digital seems to have become logical again, which is no small feat. I now need to investigate whether there are still noticeable differences between different sample rates.
In any case, I think it validates Steve's point that audible differences between computers, player software and USB cables are mainly due to common mode noise upstream of the Off Ramp 5.