I did notice a sonic difference when purchasing and switching to an ethernet Audioquest cable (it wasn't even their top of the line). It was only a 3' cable, but I swear I heard an improved difference. That cable feeds my desktop computer, which I use for streaming (has a decent soundcard in it). My other Cat 8 cables (I don't think the Audioquest cable was rated Cat 8) I use for TV ethernet streaming delivery, so I couldn't tell you if they improve audio performance or not. When running long distances, I'm a fan of shielded ethernet cables, but to reap that benefit, you must make sure they are in fact tied to ground (not always easy).
