Try another single-ended cable. You should not be getting any noise from a 4.5 meter run.
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You ought to be able to use four and a half meter unbalanced interconnects without noise problems. Perhaps there is a wiring problem with your interconnects. Use of an XLR connector will not help since the interconnection will still be unbalanced. Try connecting only one cable and see what happens.
If you were talking about forty five meters, balanced lines would be appropriate.
I have seen this before. Depending on the grounding scheme of the amps, you can get major buzzes from ICs - no matter the length. Getting around the problem may be tough. I had an easy way out with MIT T2 ICs, which never seem to buzz even with my sensitive Kora Aries and so I didn't experiment much on other ways to solve the issue. I would say any shielded cable could improve things but the problem is grounding, as you already figured out. I will think about it and if I think of anything, I will post again. Of course, MITs could solve your problem too. But lifting your ground should work. Hmmmm...
What preamp are you using?
Is the system connected to the TV? If so, remove the coax cable from either the cable box or the TV and see what happens. If the hum goes away, lift the ground on the coax cable and you should be fine. If you do not have the TV connected to the system, simply try another set of ICs such as the others have suggested. A defective cable, usually at the termination, will often cause hum through the speakers.