If you're interested in this topic, here are a few projects I found particularly interesting :

LTSpice Guitar Pedals : A collection of LTspice simulations of classic guitar pedals, useful for studying, modifying, and experimenting with analog circuits. https://github.com/cushychicken/ltspice-guitar-pedals

spiceAmp : An analog guitar amplifier simulator based on SPICE, designed to model tube amp circuits with high fidelity. https://github.com/olegkapitonov/spiceAmp

LiveSPICE : A real-time SPICE circuit simulator that lets you play audio through virtual analog circuits, making it possible to prototype and audition pedals and amplifiers interactively. https://github.com/dsharlet/LiveSPICE