Speaker cable and Interconnect BRASS Connectors

Another thing we dont know is: The kind of wire used inside the speakers. But that is another subject because cable makers and speaker makers are mostly different companies. Last weekend I was in Tokyo and I went to my favorite spot to buy some interconnect and speaker connectors but they only had brass connectors. I bought a few pairs. I will do a test at some point.

Tellurium copper (or even berylium copper) would be superior to brass or bronze, yet strong enough and elastic. Brass is a legacy, historic material but also obviously cheaper to make connectors from. While it is great for general use it's not the best available yet affordable option for hifi. 

However makers of connector still mostly refuse to accept that minimum metal mass is a way to go for hi-fi instead of massive, heavy connectors which have to fight Eddy currents. Also, heavy nickel plating under gold or silver finish plating is still preferred over direct gold/silver plating just because it gives that nicem looking eye-candy effect gloss. Seems many manufacturers prefer eye candy gloss or massive approach before what's best for the sound. However wise ones will choose otherwise if they have an option...

Are there audible characteristics that gold plated brass exhibits that anyone here has picked up on? I’m my experience with upgrading binding posts and AC connectors from gold plated brass to copper (gold and rhodium plating) that brass exhibits a distorted, more forward, less refined, harder character from the midrange into the treble. Can anyone else characterize what they hear in gold plated brass?

Not sure about what you are saying. But seeing that most connectors are made of brass, seems to me one can't tell the difference. I looked for copper connectors but hard to find. This topic is highly debatable. But to each his own. Just be satisfied with what you have. 

Bearing in mind it is the RCA Connectors Inner Pin (+) that will be the most beneficial material to be made of Copper as part of the Connector.

With a Modern Design Concert, using the most up to date Designs for Copper Metal, there are Furutech, Zavfino and Aeco RCA Male Connectors.

For a Solid Silver (+) Pin there is Aeco, which I use at present on my most expensive Wires.
There are also Silver RCA's from Furutech, but I am not sure if these are utilising a Solid Silver (+) Pin.

Costs Vary across the above RCA Connectors, but unfortunately they are Rare and Branded Items.

Mapleshade produce their own Solid Copper RCA, I have been using these as well, with a M'shade Cable I own.
I have dismantled one RCA Connector and it is a very simplistic Design.

If uses a Outer Copper Tube/Housing with a ID to match the OD of the Female RCA.
It has a Copper (+) Pin with a OD to Match the ID of the Female RCA Centre Penetration.   
The Copper (+) Pin is Mounted Centrally into a Wooden Dowel and the Dowel is of the Diameter that offers a Snug Fitting within the Outer Copper Tube/Housing.
Ensure there is a short overhang of the Centre Pin from the rear of the Dowel, to serve as Tag to connect the (+) Wire.

If a person is familiar with producing their own Cables and have an understanding of a RCA's Construction and Function, the M'shade method will be easily understood, and the cost to produce a RCA will be seen as very affordable.