Okay, you've got me thinking and now I'm going into full on hippie vision quest mode. I'm just going to throw every idea I come up with at the screen and we'll see afterward if any of it sticks.
-First thought that leaped into my mind is the Russian abstractionist painter Wasilly Kandinsky. He was undiagnosed synesthete. Synesthesia is a benign neurological condition that randomly affects about 1 in 30 people. It causes them to interpret certain stimuli through two or more senses simultaneously. Kandinsky could, for lack of a better description, see sound and hear color. His paintings to him formed a symphony when viewed, but he could never properly communicate that to his friends and critics because at the time he was alive, nobody knew that synesthesia was a thing. Nevertheless, the idea of a magic act that aims to create a sensation like that of synesthesia with music could be intriguing.
-The blues is packed to bursting with old stories and superstitions. Everyone knows the story of selling your soul to the devil at the crossroads to be a great bluesman.
-I'm currently working with a professional musician who wants some stage illusions as a way to intro or close his performances. Magical appearances, confetti productions, that sort of thing.
-Jimmy Page is a notorious occultist. There must be something there you can work with.
-Vocal coach Jaime Vendera has a book out called "Raise Your Voice" in which he teaches the technique he used to shatter glass with his unamplified voice on national TV. If you could learn the technique, demonstrate that, then try to use a magical method of shattering glass just by staring at it.
-Instead of breath as the motif, demonstrate the final phase of Daniel Garcia's Static with your voice. A sort of "acoustic levitation." I've actually been using a variant on this presentation myself for a year or two now. Only difference is that I have a way of vocalizing a note in multiple tones simultaneously. And if you don't know how I do that, I'd like that to keep to myself a little longer.
-Learning a touch of folk music could provide you with a wellspring of Old World superstitions to draw on.
I'd come up with more, but I'm trying to split my attention between this and cooking. I'm not a very good multitasker.