While I'm not a great believer in the plating on the AC plug making a huge difference I've spent some time testing AC cords and they do make a difference in some cases. The problem is all our own doing with all these switch mode supplies, wi-fi and etc. sending a lot of noise back onto the mains which the gear can pick up. Then there are the issues many are facing, even with 20 year old electrical systems, the wiring wasn't designed to handle the load of a modern home and often the grounding scheme is a joke. One solution is to just throw a shit load of money at bling cables or rather just fix the problem, either with isolation transformers or dedicated lines.