Power Cables and Wall Sockets

Don’t have much to add to what has already been said, except adding a dedicated circuit (20A), a high quality receptacle, and a power cord can’t hurt. Also, a power conditioner is a good idea, even if just for surge protection, but I’ve found that it does help quiet things down a bit. You only have to buy this stuff once, pretty much. Alternatively, If the benefit of all this stuff is purely psychological, you could go to a hypnotist and have him/her convince you that it has all been done already. Probably cheaper to just actually do it. 

...power cables can only be as good as the in-home wiring coming to the wall socket.

This is not entirely correct. The main culprits negatively affecting your hi-fi gear are devices plugged in in close proximity, so the power supply of your CD player is affecting your amplifier ( and vice versa) more than your kitchen appliance that may sit on a different circuit. The more hi-fi gear you have plugged in the same or near socket, the more cross contamination you get. And all your hi-fi gear is closely interconnected through, you guessed it, the power cables.

The upgraded wiring/dedicated high quality circuit is of course a big improvement in most cases, but it depends on the quality of existing wiring/supply.

10 gauge is a good idea for an amplifier that intermittently draws much current to power loud passages, but for class A such as SET, it is not necessary. Before you spend on "clean power" AC regenerators or filters do you hear all the claimed "dirty" noise when your amplifier is on with no source playing; e.g. phono without a record playing? AC power strips which may have filters have value for the insurance of surge and spike protection, including such protection for FM antenna cables in case of lightning. 

Keep in mind another thing. The ripple filter in the power supplies in your components become more effective at higher frequency "dirt." Such noise can be written as a Fourier series of the fundamental frequency above 120 Hz and the higher frequency harmonics are not only much lower, the reactance of the power supply capacitors in inversely proportional to the frequency and the reactance of the inductors is proportional to the frequency. The power supply ripple filter, which is already good enough to make 120 Hz inaudible allows less of the higher frequency lower voltage Fourier series terms get through. It does this better than any power box costing thousands of dollars.  

+1 dedicated line and Hubbell. Result was imperceptible noise floor and dynamite performance.