The other issue is that I strongly suspect the number of people who get up to walk across the room to adjust the main physical volume level is probably a very small percentage of listeners. Like with TV remotes, its just too easy to stay seated and adjust volume from there with your phone, tablet or remote. From that perspective, it might be easier to bring the sub volume control up to a higher level in the app -- no physical redesign of the device needed, just a programming change. That makes it both easier and less expensive to implement.