(I’ve not been reading this thread, so I might well have missed the main point of the current discussion.)
It’s more complicated than that. In the DS the input jitter is suppressed more than with most DACs because the source clocks aren’t recovered, used, or otherwise referenced. Still, even a perfect DAC will interact with each system and each input differently because of noise on the lines and/or groundloops created in the system. DACs have a particularly hard time with groundloops because the digital sources are almost always on different outlets, etc. and the groundloops have a lot of area to receive RFI, etc. and in addition digital sources almost always have a lot of noise. When the groundloop includes the analog interconnects the DAC has no control of the system’s reactions to that noise at all. Different cables can do a better or worse job at “grounding the groundloops”.
A simple test to see if it’s jitter differences on an input or noise/groundloops, etc. is to plug multiple inputs from the same source into the DS and then select among them listening for any differences. (That setup will make TOSLink perform worse because it’s galvanic isolation is wasted entirely.) In any case it’s been my experience that most (often all to my ears) of the differences between inputs disappear when you do this experiment. The PWT or DMP are good for this experiment because they ground all outputs in the same style and hence don’t give one output a significant advantage over another. Conversely if you want to make inputs as different from each other as possible only have one input physically connected to the DAC at a time.