When it comes to using USB or direct Toslink out of a computer, things like disk accesses can make a difference in jitter. It modulates the power supply after all. If you are using USB to an Off-Ramp or an Overdrive, this can potentially help. Maybe even as much as an expensive USB cable helps.
Pace-Car is another story. The jitter incoming to a Pace-Car is not important, so it probably will not make any difference. I am using a Tascam US-144 right now into my Pace-Car 2 to get USB interface. I tried several USB cables, including very expensive short ones. No audible difference. This is what I expect with the Pace-Car 2.
Steve N.