I would have preferred better wording and checking some of your details. 'It weighted twice as much' Are you saying it is maid of lead or...?
It is 20 AMP. NO it is rated for a 20 amp circuit but it can not provide any more amperage than the circuit it is connected to.
I am a big fan of good power dist. but it needs to be presented on the Up & Up.
My DIY setup is Rated at 20 amps including the built in breaker but that should NEVERE be tripped as the circuit breaker in my breaker box is a 15 amp. This is all overhead and never should come into play. I can only guess that the reason you saw some improvement was from the metal on metal connection you achieved from the new sockets plated connections and that is a good thing and good plating should provide an elimination to corrosion, which provides for a continued performance upgrade.
What most people would see improvement here is what has already been stated many time's. 20 or more amp wiring and breakers in the house circuit itself.
Upgrading power system
Since I already have components and speakers that I love, I try to make an improvement every year with something or another. Last year I bought Magnarisers for My Maggie 3.7's. Nice improvement. Immediate difference. The year before was power cables and conditioner, all Shunyata. And I always wondered why there was little if any improvement. A couple audiophiles said to replace the wall outlet. So I thought about it for years before buying a JPS labs audiophile hospital grade outlet. After removing the original outlet, I compared them. No comparison at all, the JPS weighed almost twice as much and the metal was better quality as well. The JPS was 2o amps and the original was 15. Would I hear the difference? It took all of one minute. Best $150 I ever spent. I was skeptical until I heard the difference, mostly clearer and more pronounced highs and well defined low end. Anybody else have this experience?