I am a total convert to having conditioned power (I us a Triaxis, 20/20 and a roctron xpression), and if you read this it gives a fantastic insight into both cables and earthing and, well everything including RFI, spikes the lot, and tons of stuff you might never have thought about!!!
http://www.russandrews.com/lookup/1/region/UK/currency/GBP/customer_id/PAA1487058105102VYYVBQFRISNLBPXF/article-The-Power-and-the-Glory-pgabout.htm
Read all of it and be enlightened....
Cheers
http://www.dropzone-v1.co.uk/three.htm