Very good AES presentation on inter connects and ground loops.

If everyone has not read the papers on Jensen Transformers on interconnects by Bull Whitlock I suggest doing so. An update that makes a lot of things clear was a paper he did for AES in the subject, a bit updated.  Search You-Tube for it. It is an easier presentation than app note 009.

Makes me wonder about the current fad of XLRs on home systems with 1M cables and why folks like Chord have RCA only.  Do you trust China Inc. to do it correctly? Even ASR has identified most of what they measure does not follow IEEE or AES standards let alone understand the details of the architecture.