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.
Many if not most professional producers use MIDI controllers with knobs/sliders/buttons MIDI mapped to DAW controls. As such the skeuomorphism actually plays a valuable role in ensuring that the physical instrument experience maps to their workflows. Secondarily, during production/mastering, producers are generally using automation lanes and envelopes to program parameters into the timeline, and the piano roll to polish the actual notes.
When I've historically done working sessions, the composition phase of what I'm doing tends to involve very little interaction with the keyboard, and is almost entirely driven by my interaction with the MIDI controller.
Conversely, when I'm at the production phase, I am generally not futzing with around with either knobs or the controller, and I am entirely interacting with the DAW through automation lanes or drawing in notes through the piano roll. So I don't really ever use the knob through a mouse and I've never really encountered any professional or even hobbyist musicians who do except for throwaway experimentation purposes.