Audiophiles should be happy to know that they can get them plated in silver or gold!
BTW, IMO the inexpensive Neutrik recessed RCA sockets are better that many others costing a lot more.
You can't compete with Neutrik or Switchcraft on cost, I use them in my new VolkSilver line, but if you're willing to pay more you can get far better connectors. The main issue is brass and bronze add some grain to the sound which is easily identifiable. Pure copper and silver add less.