@azbrd I am going to guess that the OP is not using the high quality Ethernet cable to deliver the last few feet of Internet service, but rather to transfer data locally stored on a server to a DAC or some other limited local data transfer.
The same argument has been leveled against power coming in off the grid and how could a high quality power cable in the last couple of feet “rescue” an already polluted AC source.
All that said, I think this logic misses the mark. A quality Ethernet cable, or analog interconnect, or power cable keep signals intact and in their appropriate lanes in a cluttered environment around your gear, so you deliver as close to the initial output at the other end of the cable as you can get without picking up or transfering interference from or to other cables or gear in the vicinity. I have found that the better I tame possible problems related to non conservative signal delivery between equipment, the better and bigger difference I notice in the next upgrade in another part of my system cabling. YMMV.
