I think changing the wire to cure brightness is a strange approach. Have you considered hanging a rug, tapestry or foam in the room in strategic places to help take the edge off? I highly doubt the wire is the culprit unless you are using very thin cheap junk. Probably the room is what needs tuning. Good Luck!
Please help: Speaker wire ?
I just purchased a JMlab Electra 905, and a Nakamichi receiver AV-10. The 905 is a little bit bright, so I've looked for a kind of speaker wire that can make the speaker sound warmer a little bit. My budget for a pair (bi-wire)is no more than $350 (I can buy used ones). Thank you very much. Tranle