And that is quite logical if you consider that a network cable is included in a digital chain. A chain that relies on clean energy to keep everything clocked tight. A chain that works with noise-levels of -140dB. A chain where small deviations are immediately audible in staging, focus and smoothness.
No DACs can do -140db noise floor, and if they could there is not a person who could hear it .
What we observe almost immediately is that the version with the shielding fixed on both sides focuses better. The version with shielding on one side seems to play a bit larger, but that is not true: the effects in the song Perfect Life by Steven wilson are placed at the same spot in the room, but are more tightly framed with the cable where the shielding is fixed on both sides.
So shockingly low levels of noise caused things to "play a bit larger", or are "more tightly framed" ... and better when both ends are connected to shield. If this person had the first clue how our hearing works, or the electronics they are working with, they would realize how silly this is. Grounding the shield at both end is to reduce EMI susceptibility primarily in noisy commercial environments with high speed transfer. However, if you are doing analog electronics, it is great way to create a ground loop. BRILLIANT! Let's take the fully isolated nature of Ethernet and introduce the potential for a ground loop then call it better?
p.s. The indicated pretty clearly I thought that every test was sighted. Given their lack of knowledge of how things work, they had already prepped themselves for the answer.