Can a z120bt be upgraded to the z130bt maps and bluetooth without having to upgrade the GUI as well ? I have a z120bt (z110bt with cnsd-110FM) and want to upgrade my maps and bluetooth but not update my GUI. I do not want to lose my sound field options (studio,hall,stadium etc...) and like the functions and options of the z120bt. I have had z130bt's and z140bt's and the z110bt and z120bt sound the cleanest and are easier to tune. Any help is appreciated. Thanks.