If your low level cables are shielded, most noise issues should be covered. I have the same power amp "problem". My current configuration is an unshielded star quad geometry for my power cable, that is self shielding by design. My TV, decoder and PC have shielded power cables. This works for me.
Maybe you want to check the puritan power cables, because their shielding is about dissipating instead of draining noise to earth.
http://www.puritanaudiolabs.com/products/mains-cables/
Maybe you want to check the puritan power cables, because their shielding is about dissipating instead of draining noise to earth.
http://www.puritanaudiolabs.com/products/mains-cables/