Hi all, I wonder if anyone can help me with a problem Im having with my SD500. It seems fine untill it gets late at night and I turn the volume down. As soon as it gets to 3 or lower, there is a horrifically loud distortion noise from the sub and speakers. Just when your trying to be quiet you end up waking up the whole block of flats. I think ive checked all my wires. Please help. p.s Is this why the guy off ebay sold it to me?