Silver plated copper

That link was about as clear as mud. No offense to you personally.

Some of the most expensive cables made, such as Jorma and MIT use copper exclusively.  IMO, some cable makers may use silver-plated wires only to be able to use the word "silver" in their marketing.  I don't think we, as consumers, have the opportunity to compare the exact same cables with copper v. silver-plated wire, so it's probably impossible to tell for sure.  But I'm open to the concept that silver-plated wire may sound different than pure copper.  

Silver is the "best" electrical conductor of electricity, marginally better than copper regarding conductivity. Silver will oxidize just as copper will, but silver will not corrode like copper. Unless I could have silver wire throughout my system (including internal wiring of components and speakers) I would not bother with just interconnects or speaker cable in silver.

Skin effect is frequency dependent and negligible at audio frequencies.

This is not exactly true, although it is common to think of it that way. So common that the fundamental was lost.

One might say that the skin effect consideration is affected by the wire or path of transmission, and that the formula we use is specifically tied to ’wire’, or lengths of pathway that are longer than they are wide..

Then that formula is ’made up’, regarding ’black box’ analysis of AC flow in said geometry of the flow.

Or, that the phenomena of skin effect, has been applied to transmission lines, the formula is created for application to transmission lines in engineering and design.... and then people take this simplistic single point and misapply and call it skin effect, when in fact, it is not. Far from it.

Skin effect is indicative of a greater consideration than the simplistic transmission line formula suggests. That the complexity of Skin effect and it’s origins were and are ’black boxed’ for simplistic engineering work.

That the black box is a far bigger thing than the simple formula or it’s generic and common application.

What is in the black box of skin effect?

There is no reason why you want to use 2 different conductors (of any type) in a cable. In fact I am also not in favor of any plating on surfaces which attach to equipment. FWIW.