Lmb: So many questions, so little time. But I'll take a flier at a few:
I don't know about recording and mastering engineers, but my sense is that the folks whose business it is to actually study the propagation of signals do indeed think they have a pretty complete handle on how signals pass through cable. For example, silver is only about 6% less resistant than copper. If you plot their relative effects on frequency response, the differences will probably fall well below the known thresholds for human detection. No law that says you gotta accept that (or believe me, for that matter).
My favorite question of yours is: Why some manufacturers, use shielding, twisting, and passive filters on their wire? Would this not imply that different cables sound different simply by design?
My answer: No, it implies that they need a gimmick to distinguish their product from the other guy's, when they both sound the same. (A bit unfair: Shielding can be important in some cases, and I don't want to speculate on passive filters. Why you'd want such filters if they do affect sound I'm not clear on.)
I don't know about recording and mastering engineers, but my sense is that the folks whose business it is to actually study the propagation of signals do indeed think they have a pretty complete handle on how signals pass through cable. For example, silver is only about 6% less resistant than copper. If you plot their relative effects on frequency response, the differences will probably fall well below the known thresholds for human detection. No law that says you gotta accept that (or believe me, for that matter).
My favorite question of yours is: Why some manufacturers, use shielding, twisting, and passive filters on their wire? Would this not imply that different cables sound different simply by design?
My answer: No, it implies that they need a gimmick to distinguish their product from the other guy's, when they both sound the same. (A bit unfair: Shielding can be important in some cases, and I don't want to speculate on passive filters. Why you'd want such filters if they do affect sound I'm not clear on.)