I bought 1 Black Sands Silver Ref 5 cables on the AN group buy soon after I started posting here. I shocked myself that I was gullible enough to spend so much money on power cables when I was already content with the vinyl POS that came with the amp (50W Cary integrated.) I figured I did it just so I could be one of the guys. Then a month later I got some better mono amps and needed another PC. John was gracious to extend the GB price again, and I was able to compare the vinyl stock cords to the Black Sands. It was a minor but obvious improvement, so I found a way to justify the cost in my head.
I have since heard PCs that work better than the Black Sands, but I haven't upgraded yet. These are good enough for now. The best PC I have ever heard is JPS Kaptovator. It's unreal what it does, but it's wicked pricey, like $1200/m? JPS PowerAC+ is better than my Black Sand for the same price, but I keep the BS because I like having something from John in my system and it's plenty good enough for my needs.
I mostly listen to Sol's integrated with captive vinyl cord, it is my favorite amp, so I question the "need" for upgrade cords. He is building a new prototype with IEC, so then want becomes need.