To the original point... solid silver is expensive and occupie only the top of a cable manufactures line. My Wireworld Platinum speaker and IC cables are silver and sound wonderful. The speaker cables are much richer sounding than the Nordost Valhalla 2 copper/silver cables they replaced. Audioquest's top of the line cables are solid silver and violently expensive but highly regarded for example.
Pure Silver Wire
If silver is so good to use why do we not see solid silver speaker cables? Price is not that high- 10ga diameter pure silver 6ft is just under $300. That makes a pair of speaker cables about $1,100 for material. I see the price of some of these cables on the market and $1,100 is a fraction of their asking price.