Good outlet for amplifiers

@gdaddy1 I hear you… But I would also have to construct my own cables in that case. I’m using power cables that have plugs on them.

Hubbel 5362. These come in 15 and 20 amp versions and are better made than typical outlets from Home Depot. They are all copper and are heavier duty than a typical outlet. They are under $15 each on Amazon.

They are not copper, they nickel plated brass. Of course brass is half copper. 

In order to isolate the ground, however, would I break off the tab that wraps around one side of the unit to the ground lug? 

But why the priority for isolated grounds? Why not use Puritan groundmaster instead. Shunyata or nordost have their grounding systems also for much more money. 

@jea48 what are your thoughts on isolated grounds? 

I confirmation of others before me, the Furutech GTX-D NCF(R) Ultimate Nano-Crystal Rhodium-Plated AC Duplex Receptacle produced an audible difference.  
In reviewing your system, I do not see power conditioning listed.  I recognize your post focuses on outlet recommendations, but consider a power conditioner within your means from Shunyata or Audience.  Well kept preowned is good.  IMHO, more of an improvement across the board than an outlet.  

@pinball101 Wouldnt I get a better connection, at least to the first outlet, by going directly into the outlet rather than creating a pigtail in the box? That’s what I was thinking and why I would Daisy chain. Because the most important outlet will be the first one where the two amplifiers are set  also, this quad installation is the end of a circuit… So I’m not too worried about other outlets further downstream.

I can't speak to the benefits of direct connection vs the pigtails in line with the connection.  But based on your configuration being at the end of the circuit, I would not bother with the pigtails either.  

I'm not familiar with the isolated grounding you are referencing so I can't speak to that either.