I'm feeling really lame as I had never even heard of Oyaide cable before this thread, and while I did run two dedicated circuits off the same phase, I only used 12 ga Romex...Did not run $40/ft wire but did wire 2 dedicated duplexes with 10ga Romex home runs to 2 dedicated breakers in the master panel with attention paid to their being wired in-phase. I too noticed a significant improvement in system sound quality doing this.