Replacing/Upgrading AC Outlets

Hospital grade is more than good enough for any hifi application. So-called “audiophile receptacles” are just a euphemism for “sucker receptacles”. By the way, spec-grade is more than adequate and well worth the 10x price of your common $0.79 receptacle. Beyond spec-grade, the law of diminishing returns applies. 

I’m sure that manufacturers of receptacles employ metallurgists to ensure the widest comparability in plating alloys with the various metals commonly used in equipment plug blades. That said, the el-cheapo 79 cent receptacle designs probably benefit less from the metalurgists’ attention than the better spec-grade and hospital grade product.
p.s. Thanks Elizabeth for the Rip Vanwinkel reference.... gave me a chuckle. :-)