Power cord is one of the more incomprehensible things I’ve experienced in audio. How can a cable that is not a part of the audio signal chain make a difference in sound...but it does
An amplifier does not enlarge the input signal, rather it makes a large copy of the input signal using the electricity from the mains to create the copy. An amplifier is actually a copying machine of sorts. The input signal never gets to your speaker but dies in the amplifier.
What goes down your speaker cable consists 100% of what comes into the amp via the power cable. In a sense, the AC is part of the signal path and we get tangible benefits when we optimize it.