I have each one.of those plugs. Theory one I have not bought is the first 48 plated in silver. I have a few sets in rhodium and a few sets of the very best rhodium plug as well. Lol I cheaper out and bought four sets of the 48 rhodium ones and I have five sets of the Top one as well in rhodium plating. I also bought one set of the 15 in copper. I have a neotech gold as well have not tried that on anything yet. The basic copper plug set to me has the resolution of the rhodium plated ones and the musicality of the gold plated one but not the detail of either of the other two. I bought some of the carbon fiber covers I slipped over the plug and iec ends. That did make them a bit better. Where I liked those covers the best was over the 46 gold plated plugs the resolution got better and still had the swing of the gold plated ends. Also I have some of the best rhodium receptacle s and some of the best gold receptacles. Some components I like a rhodium plug into a gold receptacle and vise Vera. Some sound best with all gold or all rhodium in the chain. Lol that takes lots of time and listening to decide which way to go.
Regards