Chances are an expensive cable will NOT fix it.
Low hum are normaly caused by a ground loop. Do you have the Ipod plugged into a power brick AC adapter? If so does it still make the noise when you unplug the power brick and just use the Ipod batteries.
If the later is the case, are you plugging the Power brick into the SAME power strip as your reciever? If not try that see it that fixes the problem.