Do pure copper banana plugs make a difference in the quality of the speaker sound.

@redwoodaudio - you are correct.

Fortunately - you can "adjust" the KLE Bananas quite easily.

I use an old banana plug similar to this one...
https://www.amazon.ca/GearIT-Premium-Braided-Speaker-Plated/dp/B0713ZDBM2/ref=redir_mobile_desktop?i...

I removed that little piece of wire on the pin. The shaft of this banana then fits nicely inside of the KLE Banana, making them expand ever so slightly to allow them to fit "Snuggly" in most binding posts.

But as I said, they are more delicate than many other alternatives, but they sound great

Regards - Steve

  The correct answer is what you like based on your system in your house . Beware of the people that tell you what you will hear in  “Absolute statements “. I use some bananas and some spades . For me in my system , silver on the connectors or in/on the wires ads a brightness to my system in my listening room that I don’t care for . If you are fortunate enough to have friends that will lend you cables to try , take advantage of it . I personally don’t believe in the NASA based article that “ wire is wire “. But I have a budget on the modest side and don’t run high priced wire . I’ve had good luck at my price point with Anti Cables , Morrow , Cardas, and Audioquest. I’ve experienced noticeable improvement with break in too . Morrow interconnects take 400 hours . I also believe in cleaning and treating my connections. This is one of the many experiences we get to enjoy building  our systems . If this doesn’t drive you crazy, explore tube rolling . Best wishes and happy hunting . 

Rhodium is the best material for contact surfaces. It is harder than gold. Rhodium is a good conductor (although this is not important for contacts), and rhodium does not tarnish. Second is gold, since it doesn’t tarnish as much as other materials. All military connectors use gold. Rhodium is too expensive. But gold is soft and not a great conductor compared to copper or silver; so it is generally a poor choice for the wire itself. Silver is the best conductor for wire.

Btw, “white gold” jewelry is just rhodium plated gold.

@cakids - I found some different information,,,

White gold was originally developed to imitate platinum (a naturally white metal). White gold is usually an alloy containing about 75% gold and about 25% nickel and zinc. If stamped 18 karat, it would be 75% pure gold.

and

Rhodium is a chemical element with the symbol Rh and atomic number 45. It is an ultra-rare, silvery-white, hard, corrosion-resistant, and chemically inert

But you are correct in that Rhodium is used a lot in jewelry, but in comparison to silver, coper and even gold - it is a poor conductor

From the table of Conductivity...

1. Silver’s conductivity is 106,
2. OCC copper is around 102
3. Copper is considered the reference at 100
4. Gold is 65
5. Rhodium is 38
6. Beryllium Copper is 22 (commonly used for plug contacts)
7. Platinum is 15

BTW - Conductivity is VERY important for contacts

Also - If the contacts of a plug are Gold or Rhodium plated, then a substrate plating is required, which normally has an even lower conductivity rating than the plating materials.

Regards