I have just noticed that my Marantz DVD player and Amp do not have an earth pin on the IEC connector. I opened the plug and can confirm there are just the live an neutral wires. I wanted to know if: 1 - What effect this would have on the equipment (if any)? 2 - Would this cause a hum in my subwoofer? 3 - Would it still be worth me upgrading my mains cables? 4 - Am i being silly? Thanks.