Design a digital controller circuit in connection with a USB controller

I am working on a Microphone Preamplifier based on THAT1580 chip, which is digitally gain controlled by another chip THAT5173. The digital part is based on THAT design for which I attached the PDF here. What I need from you is to design an additional circuit which will control the THAT5173 through a manual encoder, so the preamp user will be able to use the USB port, or a front panel encoder for changing the gain. The gain will have to be synchronized on both encoder and USB controller. Also the circuit needs to show the set level on a 2 digits display. I will accept another USB controller if you consider it a better option. Also I am open to other ideas how to achieve this. You will have to provide the electronic schematic and a PCB(Gerber for it) that will attache to the Main preamp board through a connector. Also you will provide the programming software if any. Will discuss it in details with the winner freelancer.