I have a step up transformer that has been loaned to me for quite some time, but it's incredibly picky about where it is located. If it's next to nearly anything, it hums very loudly. When move to a chair in front of the system, it's pretty quiet. But every IC cable I have is non shielded. Is this likely to be the problem? If so, what the shielded IC cables are you guys using? Should I just get a Blue Jeans cheapy to see if this is the problem, or look for a recommended used cable?