The unit looks great and not many changes recommended physically other than the ones suggested above. In terms of the display when used as preamp it should show the volume in large font for easy reading from a distance. Hope it comes with a basic remote for changing volume and input selection.
This is great news, I am in the process of making the same by combining your products with raspberry pi based streaming software. Will be great if your team can create the same, looking forward for your product release.