I've been using DH Labs T-14 speaker cables for several years. I find the sound to be a "subjective improvement" over the 12g copper cables I used before. I'm very satisfied, so no plans to further experiment with speaker cables.
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.