Hi @skennedyXTYKA,
Welcome to Fusion!! You are speaking my language, I enjoy building pedals and have built a few. So the first question is pretty simple in Electronics design you can often represent a potentiometer as a resistance or a couple of resistances.
Now I hate to be a buzz kill but SPICE simulation in Fusion can't currently (at least not easily) take a wave file and then run in to the circuit and get an output. With that said even if it could, the resulting output would be a poor simile of what the actual circuit would sound like.
That's not to say circuit simulation isn't useful, but if you are expecting a digital twin of the analog circuit we are not quite there yet. What you would typically do with the circuit simulation is feed simpler signals to the circuit (sine, waves, square waves, etc.) and you can get a waveform of the output to see if the design is what you are expecting. The other part of this is the quality of the models, if the models are generic then you won't get a good reflection of reality.
All of this to say, your breadboard will still be your friend but the sims can help you get to your final design faster.
Let me know if there's anything I can do for you.
Best Regards,

Jorge Garcia
Product Support Specialist for Fusion 360 and EAGLE
Kudos are much appreciated if the information I have shared is helpful to you and/or others.
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