My basic idea is a world with a “string theory” where the strings are actual metaphysical musical strings that manifest magical effects when “plucked” a certain way.
Sympathetic resonant induction. The interaction of frequencies is the underlying principle of both string theory and music theory. Assign various “flavors” of string which resonate with different elements/colleges/domains, spells sung or played properly in tune manipulate the fabric of reality.
Develop a musical language, look into Solresol and Enochian for some inspiration. Include monasteries with gongs and singing bowls, church organs, choirs, anything like that. Religions lean heavy into “the Word”.
I would definitely involve the Tritone, a chord that was considered evil by the church
Ocarina of time but with strings?
Reference Kung Fu Hustle:
Or Multiverse of Madness:
Wouldn’t you go about it like any other world with magic? Just switch out the staff/wands with instruments(guitar/violin) and the gibberish words with melodies.