Replacing generic RECEPTACLES

I can say my Furutech GTX gold duplex cost $145 each (on sale $70 off regular price ends July 31) I have two installed and a third on the way.I may also buy one GTX-R Rhodium plated.later. My setup has been geared to the greatest clarity I can find.. And had become a bit lean sounding. The gold Furutech were just the ticket to warm it up a little. All around much better, though a little too much bass for my apartment on a few recordings. But for the majority, perfect.          
I have nothing to say about outlet covers affecting sound. LOL Only that I do use solid brass covers from Menards. $5 $6. (non magnetic)

@dynaquest4......Off the top of my head the cost was about $235 for each of the Furutech GTX-D-R .  The Oyaide WPC-Z Aluminum base with carbon fiber cover $235 ? And the Oyaide WPC-Z2 double Aluminum base with carbon fiber cover $350? And even though they are and look and feel very industrial and look great i did not buy them for the looks. To me and my ears between the Furutech GTX- D-R and the Oyaide WPC covers is like adding a $2500 power conditioner. It really does some incredible positive things to the sound. My next tweek is the Herbies tube dampers for my ARC Ref 6 preamp... 

Oyaide WPC-Z and Z2...... High performance mounting frame and panel....The appearance of the WPC-Z attracted audio enthusiasts and created a strong impression of mounting frame for wall outlets. In 2007, the long awaited double type base, WPC-Z2, has come on the scene. The most important function for high performance mounting frame is attenuating vibration dampening property. The hybrid materials , each of them has different resonance frequency, perform passive vibration suppression to maximize performance of the Furutech GTX -D-R .Furthermore, carbon fiber reinforced plastic, the material of face plate, has functions of static protection and electromagnetic shielding WPC-Z series are the ultimate optional accessory for unlocking unlimited potential of the Furutech GTX D-R. 

Well it sounds like you are having fun with your hobby and I suspect there are other hobbies in which people spend gobs of money on tweeks that are of questionable value. I have no problem at all with hobbies and spending your money as you see fit. What I do have difficulty with (as I’ve mentioned before) are rave reviews (like yours) that tout a tweek as if a deaf person could hear the dramatic improvement. This, I think does a disservice to new, inexperienced readers of this forum.

If a "special" plug (OK....receptacle sounds better) did squeeze out any actual improvement, I submit it would be:
1. Very subtle (like with exotic cables, interconnects and power cords); not to the over-the-top degree to which you claim.
2. Nearly undetectable unless you could switch back and forth between plugs (probably electrically impossible) in an A/B type test. Audio memory, as I hope you know, is so perishable, it is almost impossible to remember the nuances of an audio track unless the transition is near instantaneously.
3. Expectation bias. The more you spend, the higher the expectation.

I’ve been into audio for a long time and never thought I see a day that good equipment would sound so lacking that you would have to spend $900.00 on a plug. But considering what cables have done, I should have suspected. Next? Pressure suits you can wear so that after you suck all the air out of your room you can listen in a vacuum?

BTW....not looking for a debate; just posting a counter-opinion for the record. Like with politics, no one is going to change their mind but we can influence those who have not yet reached an opinion.

@tattooedtrackman while the Oyaide CF faceplates are great their weakspot (endemic to the design of US outlets) is the single screw fixing in the center leaving the edges free to vibrate. Try applying small strips of FoQ damping material across the edge of the CF plate onto the aluminium surround and you will be astonished at the improvement. When it comes to managing vibration everything matters it seems.

Also the screws have a tendency to strip so changing faceplates can be a pain, this may be an interaction with the underlying outlets (I use SR Blues, Reds and Blacks and the stripping has happened with reds)