Then what's left? What else can differentiate one power cord from another?Well - it's a lot more complicated - to start with, I have found the following affects all cables - not just power cables...
- Connectors - you need quality connectors with plated solid copper pins - my preference is silver plated Sonar Quest connectors - the IEC plugs clamp like a vice
- Quality wires - either OCC Silver or OCC copper - the fewer strands the better, but solid copper or Solid silver wire will fracture if the cable is constantly moved - I now use 4 strands of solid 18 gauge OCC copper for amp power cables and one strand of 18 gauge solid silver wire for source components. I use a different type wire for neutral and ground wires.
- Insulation that has a low Dielectric Constant (D.C.) - Teflon is too high at 2.1 - below 1.5 is best - I now use wire from VH Audio that has mains rated (600v) AirLok insulation with a D.C. less than 1.45
- A well designed cable geometry that mitigates cable related noise - I use a Helix geometry, but there are others to consider.
If you want to see inside a well designed power cable take a look at the Inakustik web site..
https://www.in-akustik.de/en/cables-and-accessories/reference-selection/power-cables/
Nordost also build great cables, but they don’t share their design so openly
I build my own cables, so I can control every aspect - and I build to the requirements of each component.
One power cable does not necessarily work well for every component
Hope that helps - Steve