Just an fyi to anyone making or thinking of making one of these: Turning a knob with a mouse is the worst interface I can think of. I don't know why audio apps/DAWs fall so hard on skeuomorphism here when the interface just doesn't make sense in the context.
I'm racking my brain thinking of what a better interface would be for selecting a number between a range of values, where the number is a point on a continuum and not any specific value, and can't think of one. The equivalent "traditional" UX for webapps would be a slider control, but that's functionally the same and you'd be going against many years of domain-specific common understanding for not much benefit.