I've been trying to understand what you are saying. But first of all, respectfully, I think the relationship of the size of conductor to resistance involves a square and a determination of output impedance is more complicated that just being the product of LCR. I am not an EE so I struggle like many others with the complexity of electrical circuits.
But it sounds to me like you are saying that the benefit of a short, fat wire (a bespoke power cable) connected to a long thin wire (the household romex) carrying AC current is that it acts kind of like a capacitor in that it stores up current as a reserve in instances when the amp needs more. My problem with this vision is that in an amp's power supply the AC is converted to DC and if the amp has a linear power supply built into it (and here I am thinking of a solid state class A amp, in fact I am specifically thinking of a Pass Firstwatt F6 which I am currently building) then it includes a generous bank of capacitors and resistors specifically to smooth out the dc current after it has passed though the rectifier that converts it from the AC into DC. I believe that same capacitor bank also acts as the current reserve for the amp. I suspect this reserve is much, much larger that what could be conceivably stored in a 3 or 6 foot length of power cable. So it seems to me that either I am mistaken or you are mistaken about how this all works. I tried searching for a more definitive answer on the net but I suspect I just did not know how to phrase the "fat wire, thin wire" question correctly.
For what it's worth, I don't know if you have ever had the chance to look inside an amp, but the wires carrying the current as well as the outgoing signal are pretty thin. Also while reading up for this amp building project I recall Nelson Pass, a man for whom I have great respect, making a comment regarding wires to the effect that he has nothing against nice wires and if people give them to him he uses them but beyond that he seemed not too concerned.