Is there a difference in sound between copper and silver digital cables, or purely in the implementation?
Yes there is a difference. But implementation definitely still matters.
Take for example Synergistic Research Element cables. Element Copper and Element Tungsten are different only in the two metals. Its pretty easy to hear the differences. This is just as true by the way whether its speaker cables, power cords, analog or digital. Element CTS combines three separate cables, one of each element, and yes what you hear is the best qualities of all three combined.
So there clearly are differences in sound between copper and silver. But compare either SR Element with another cable using the same metal but made by someone else and it will be obvious just how big a role implementation plays in it.
It still boggles my mind that in this day and age we are still talking about digital as if it mattered. Because it doesn’t. Please see above. Wire is wire. How it sounds digital is how it sounds analog is how it sounds between components or the power from the wall. Or inside the speaker for that matter. Its wire. It matters. Wherever it is.