Lead is one I've had lying around, thought it was to blame so spent a tenner on a new one. Doesn't solve the problem so thats going back for a refund!
Player is a Soniqcast Aerio, will double check the output with headphones but I've never noticed a problem. Also it has two jack sockets so you can listen with a friend, but swapping to the other doesn't fix it.
http://images.google.co.uk/imgres?imgur ... l%26sa%3DG