I’ve used the supplied stp cables and my homemade utp cables between my k30 and ex with no difference in sound. Both my Antipodes power cables are grounded. (I’ve changed the plugs so was able to confirm this). I believe they run the ethernet shield to chassis ground as well as the power ground. As long as both the units come from the same receptacle there should be no ground loops. If the ethernet cable feeding the server is stp and comes from a switch in another part of the house there could be ground loops. Utp cable or fibre feed to the server will eliminate this. Probably the supplied cable is stp in case of induced noise from other equipment to the server/player.