Recommendations for 20 amp electrical outlets

I just had my house rewired and installed 2 20-amp outlets for my stereo wall. I used Monosaudio Audiophile Duplex Receptacle 20 Amp 125V Pure Copper Audio Wall Outlets bought on Amazon. These were wired with all 3 wires for each duplex outlet pulled back to the panel (no common ground). They’re reasonably priced and I got an almost noise free connection and my sound definitely improved ( and everything I have is connected to a Furman conditioner).

To warn everyone in the US, under the NEC code all new electrical outlets must be tamper resistant. You will be hit with this if you need an inspection for the work. Unfortunately I haven’t found an audiophile 20-amp outlets that’s tamper resistant if they’re round, only white square (decora). 

I’ve use the audioquest and it’s seems very well made, also comes with silver spades for your ground. I also use the Shunyata and can highly recommended that as well. One feature the shunyata has is the ability to grip the plug without it sagging and pulling out of the wall contacts. Great for heavy power cables. 

I use a Oyaide R1 Beryllium outlet. It has great grip for heavy power cables.

My view is that there are two main considerations about receptacles (also includes cord plugs and IEC connectors).

First, what is the base metal used for the product. There is basic brass that is the norm for commercial products, Hubbell, etc. The most basic form of brass is about 1/3 zinc and 2/3 "regular" copper. Next is Phosphor Bronze that is found in products from the companies that offer audiophile caliber receptacles and cord ends. Phosphor Bronze is a high copper content form of brass. Next is "pure copper". Well, there's more than one kind of "pure copper". Beryllium copper seems to be the top dog for receptacles and cord plugs.

Second, what is the plating? Nickel, gold, silver, rhodium, platinum, palladium or some combination or no plating at all. Each has it's own sound character. 

Since everyone has their own perceptions and preferences, you have to hear these different products first hand. While my preference is for un-plated receptacles and cord ends most of the time (I do have several Oyaide 004 cord ends on several power cords), many audiophiles like the sound of the various plated choices that are available.

For me, un-plated brass and plated brass are non-starters. The more copper and the better the copper is, the better the sound. The outlier here is the Maestro outlet. I seems to be some form of brass but, does not sound like a typical brass receptacle.

I use two different receptacles at the same time. My main system has two dedicated power lines with a two gang box on each line. Each box has two receptacles. Each box has one Maestro receptacle and one Oyaide R0 (not the R1). The R0 is an un-plated beryllium copper outlet (grips tightly). This allows me to tailor the system's sound more than I could using just one particular outlet only. The Maestro is somewhat brighter and a little more open sounding.

I choose, primarily, to use un-plated connectors since I am extremely sensitive to high frequency problems such as brightness, brashness, harshness, etc., etc. In addition, to my ear the system is more relaxed sounding than it would be otherwise.

I met Galen Carol (Shunyata) at the 2018 AXPONA and he told me a couple interesting things about outlets.

1. He recommended Hubbel 5362 outlets. He said they will perform as well or better than any exotic outlets.
2. He didn't recommend hospital grade outlets because they are built to withstand chemical corrosion as their first priority. They have stainless contacts which do not conduct electricity as well as copper.

I'm building a new house with an audio room and I will be using Hubbel 5362's for the three dedicated 20 amp circuits. However, I will have to install them after the electrical inspection because they are not tamper proof as @pcolvin mentioned.