Redkiwi:
Thank You!, for your response to my query. Your experience is greater than mine, but....I am just getting to the point at which I was beginning to wonder about the characteristics you describe as "brighter and with a coarser grain". I have made too many changes (in the midst of a house remodel) to be sure, but your words strike me as having the distinct ring of truth.
Your methodology of testing Romex makes perfect sense. I will definitely be using your method.
I can understand your remarks about grounds. I had not considered the issues of the voltage variation, but I can easily understand why you would find differences. For myself, I have found the greatest success with dedicated circuits coupled with true isolated grounds, seperated from the remainder of the household circuits. I understand the issues of potential ground differential, but I have placed the rods in close proximity, and have done my best to create identical parallel systems.