@atmasphere with all my respect to you and your wonderful creations, I like to add more details to this, somewhat important, discussion:
1) I think it’s pointless do discuss effects caused by “most cables/cords/wirings” without bringing up technical parameters, such as R/L/C per foot or meter, for specific parts. Power cables in my usage are better than my house wiring, thus have less voltage drop per length. Other important variables in power interconnects are connections between wires and terminals, and between mics. contacts.
2) Amplifiers with transformers/rectifiers/capacitors in a power supply, draw current at very short time over sine wave. Worse, the better the amp is the shorter time/phase segment current is drawn. The best power block designs I’ve seen and worked on, current drawn only 1..5% of time. Such circumstances make even 20A certified wiring/outlets not enough to reduce IR drop over AC supply, which can exceeds 10 Volts! Thats why house wiring shuld be the first step to improve sound system power delivery, to reduce IR drop caused by 50A or more short current spikes.
3) Transformers’ used in the amp’s power supply are the most IR-dropping devices in the chain, that’s why top brands use very expensive, well performing, heavy ones. Priciest part of Parasound JC1 for example is transformer!