@asctim There are Graphene cables on the market now.
https://www.thesoundadvocate.com/2019/08/reviewed-cerious-technologies-graphene-extreme-cables/
32 pairs of speaker and RCA cables measured and listened to
I am not sure if this has been posted here before, but this is pretty interesting.
These guys measured and (blind) listened to, 32 pairs of RCA cables and speaker cables. And found both measurable and audible differences.