they act as equalizersArgyro,
What is *wrong* with even the super high-end audio systems is the contaminated AC and an atmosphere full of RFI. And the high-end market is full of products, including conditioners and special power cords, that are aimed at solving those problems at every link in the chain from the circuit box to the speakers.
Also, usually the word "equalizer" refers to a devise in the audio signal path. So, your conjecture/belief about power cords would be more appropriate for interconnects and speaker cables. Since the audio signal path does not go through the power cords, the cords cannot act *directly* on the audio signal. However, some power cords, like the Elrod Statement Gold, are designed to reduce noise on the AC stream. The lower noise floor then allows the components to reveal what was masked by the noise. Therefore, power cords can *indirectly* affect the sonic presentation. Perhaps, you are using the word "equalizer" in a very loose sense to include anything that affects the sound, directly or indirectly. Since barometric pressure, temperature and humidity affect sound, would you call these equalizers? To avoid uninteresting semantics, I prefer the more traditional use of "equalizer".
The goal of every change that I make to my audio system is to increase realism. In the last 4 decades, I attended well over 600 live classical concerts and I'm familiar with how the different instruments can sound. That experience has been most helpful for the evolution of my audio system. In my system, the Elrod Statement Gold power cords significantly increased the sonic realism and my enjoyment. For me, that is an excellent bottom line.