OK I'll throw this out there.
Over about the past 6 months I have found that insulation on wire actually dulls the sound. Yup, it does, to some degree.
My latest DIY power cords (with PC bare wires soaked in grapene), digital IC, analog ICs, speaker wires and speaker internal wires all use a special type of bare copper wire separated from each other with a special material, creating mostly an air dielectric. The result is a much lower capacitance cable (50 pF per 4-foot 10 ga power cord, 29 pF per 4-foot IC, measured with a capacitance meter) and sound has really opened up using this approach.
Could it be that the sound artifacts you are talking about are to some degree not because of the wire itself, but the insulation on the wire? Since we have been using insulated wire from day 1, could it be that insulation was assumed to be sonically transparent when it is actually not?
If so, then just about all the cables you buy that use insulated wire has this problem.
Hmmmmmm... pondering...
Gary