But Schubert, if how this stuff works can't be technically explained, or can only be partially explained, upon what principles and upon what basis do the designers of the power cords design them?
The likely answer, as I see it: Upon some combination of trial and error, using a relatively limited number of systems; pet theories, whose applicability across a wide variety of systems is unproven; and, perhaps most significantly in the case of expensive power cords, by overkilling every parameter that the designer considers to possibly be relevant. With the degree of overkill increasing as the price of the cord increases.
Implicit in my earlier post in this thread is the thought that the system and component dependency of those effects that ARE technically explainable, as well as the fact that those particular benefits are obtainable at relatively low cost, can be expected to loosen the correlation between power cord performance and power cord price. Each of the three approaches to power cord design and development that are listed in the preceding paragraph can be expected to further loosen that correlation.
Regards,
-- Al