"Colloidal copper preparation compounds". They work for silver and other metals as well. "Kopr-shield" is one. It's an anti corrosion treatment for connections that will not only keep copper from oxidizing it will enhance the resistance properties, "lower resistance" of the termination.
There is another product whose name currently escapes me. It's a high silver "powder" content, anti-oxidation treatment. I believe "Parts Express" carries it. Why audiophiles don't use this more often escapes me. That this works is a quantifiable fact. Easily measured with a meter as resistance but that measurement will not give you any given frequencies loss or corruption, "one type of distortion". Which is a factor when talking about line transmission. Most know something about frequency induction along the signal path but not so much about signal degradation and corruption. If a given frequency degrades enough, most will think it wasn't there to begin with. And if corrupted until it's simply distortion we think it's something to get rid of when in fact the opposite is true. It needs to be saved. Therefore the goal should be insulative in nature to protect the sanctity of the source signal. That would also help with induction of "other than true source" energy. "Ramble, ramble, ramble...." So those are my 2 cents! And if you don't at least try this you should be relegated to using only lamp cord for speaker and signal wire for eternity! Or at least until you can come up with the $27 bucks for the 16oz. container of said compound. Which ever comes first.
