hi almarg:
there may be cables which produce consistent results from one stereo system to another.
perhaps you haven't found one, but if your hypothesis is as stated, and un proven, i.e., an opinion, all it takes is one exception, i.e., one cable which gives consistent results when placed in different stereo systems.
it is impossible to listen to all cables and so your propositions are based , i assume, upon inductive reasoning.
i have heard cables which have similar effects in different stereo systems.
for example, a cable that has some subtractive colorations in one system, will probably exhibit these colorations in other stereo systems.there are so many variable that it is highly conjectural to propose cable--stereo system relationships as if they are facts or knowledge.
it's more useful to have an open mind and not be bound by constraining propositions.