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

Whatever I have at hand! Usually the cheap stuff! Monoprice!

Free yourselves from the neurotic obsession with conductor materials! 

I've used a couple of different connectors

For spade connectors I use Furez silver plated copper - they have proven t be the best sounding spade connectors I have tried

For Bananas, Furez also produces a nice Silver Plated Banana
- BUT the Bananas plug I now use is from KLE Innovations - it is exceptional and are great for installing jumpers on Bi-wireable speakers

I found that silver plated copper provides the best details and clarity and if the silver plate does tarnish then reseating the plug will effectively clean the tarnish at the point of contact (if there is any)

The black "Tarnish" on silver is the silver reating with the Sulpher in the air to produce silver sulphide, which actually conducts electricity, unlike the tarnish on bare copper, which MUST be cleaned/removed.

I did use the more affordable gold plated brass and Berylliam Copper type of banana for a while, but the silver plated copper are better - to these ears anyway

I use silver plated copper Mains connectors on my mains cables

And the RCA's from KLE Innovations are the best RCA's I have tried to date

Hope that helps - Steve

Thanks for your informative reply.