Replacing generic RECEPTACLES

According to UL and NEMA, the only difference between a 125 vac 15 amp receptacle and a 20 amp receptacle, is the plastic cover governing the type of plug it will accept.  I installed two dedicated 12/2 lines, each having hospital grade single 20 amp receptacles, for my monoblocks. They’re both on the same buss at the breaker box.  All my “hi-fi” receptacles are on the same buss.  As far as the receptacle covers influencing the overall sound, that’s something I’ve never considered.  Unless you have a Faraday cage, we are all exposed to unending amounts of EMF and radio waves going through us and our listening rooms at all times.  IMO, such nuances as special receptacle plates have little effect on the sound.  I do realize that if you add a lot of subtle tweeks to your system, they add up, but to diminishing returns.  I know-unless one has tried it...etc etc.

@ Cleeds-Just quoting NEMA. I admit I haven't disassembled a receptacle. Never saw the need. 

@ Elizabeth. Kudos to you for disassembling a receptacle. I used to do this for a living and never contemplated doing that. I think the receptacle you described is a little over the top, but glad you like them. In a high current draw situation, if the connector, being the cord in this case, doesn't generate any heat at the connection,  you're good. As I said earlier, a lot of small tweaks put together, can and does make a difference. My view is, as I said, you have diminishing returns after a while. I'll have to say, you're really getting down to the nitty gritty. I guess if you know you have done everything you can to improve your sound, it's very comforting.