Any Difference Between Gold and Silver RCA/XLR Connector Plugs?

Well, silver is the best conductor of electricity; gold isn't even as good a conductor as copper. Gold plated is a marketing gimmick. The only advantage gold might possibly have is that it will not tarnish or oxidize as readily as silver or copper. You made the right choice.

I've read one study showing that there is a tiny effect when going from one material to another, so sticking with gold contacts is probably a good idea.

I agree that sticking with whatever material is dictated on the input jacks should be maintained on your interconnects as far as the issue of dissimilar materials are concerned. I'm sure there is a differential in resistance when using different metals in an electrical path but is probably negligible. It is likely that the conductors on the pole outside your house are aluminum and maybe copper from the pole to your house and likely copper wiring in your walls. Might be interesting to know how silver on the pole and the house feeder and the house wiring would sound. Maybe they have that in Saudi Arabia.

As the French Chef says: "No diffawrance!"

When’s the last time you had your ears candled?