Completely agree shadorne. :) The plethora of gizmos to address issues with USB transmission is a glaring example of adding band aids in an attempt to address endemic weaknesses of the technology as well as in component design/implementation, but I think there is more to digital cable influence than that.
Re: the influence of different digital cables on sound quality, as I think you have said before, this has a lot to do with the quality of the particular component’s input design and the clock implementation. Perhaps most sensitive is the component’s USB input design/implementation (vs S/PDIF or AES/EBU) as there are more potential demons to conquer with USB data transmission. Overcoming potential noise issues with USB’s unique use of the 5V power lead in the same cable/connector interface is a challenge with USB and also that most USB designs are asynchronous, thus depending on the data transmission integrity of the source and the cable to avoid data loss that impedes the DAC’s analog reconstruction process. Maybe completely jitter related as you say a lot but I am not convinced that there is not more to it than jitter. Things like impedance match/mismatch, RF/EMI rejection and signal isolation to eliminate noise riding on the signal, etc.
Anyway, very nice to agree on a balance of reasoning and listening as the superior path to better results.
Dave