Good question OP. Especially because when I go to demos by factory reps or to audio shows, they almost never use stock power cables. Would be nice to hear from a manufacturer on this thread.
One thought. The performance of power cables (and pretty much all other cables) depends on the environment in which they are used. What are they connecting and how many other kinds of gear and cable types will be in proximity behind your system and in what configurations? My feeling is that the full magic of better cables is revealed in your system by how well they keep signals and potential interference separated. While a manufacturer could maximize performance of a power cable for their amp or other gear on the test bench, they have now idea what specific environment that cable will experience in various users homes. Better to let the customer figure out what works best supplying current to their gear in their room next to their ICs, speaker and digital cables and other power supplies and circuits. I have 9 separate pieces of electronics in my rack with 8 power cables, 2 DC cables, 5 speaker cable sets, 3 IC sets and three digital cables. Both my DAC and phono preamp have separate custom power supplies. How could a manufacturer anticipate and maximize the design of their power cable to function in this environment, your environment, or someone else’s system?
As somebody who has tried a lot of power cables and built a few from component parts, for me it is all about synergy in my set up. Generally, the more better cables I have added, the better things sound, but it takes a lot of tweaking and trial and error to get remarkable results. Not sure an original equipment manufacturer could prejudge what would work best in everyone’s system, so probably just prudent for them to supply something inexpensive that makes sound come out and doesn’t catch fire.
kn