Many times I am sound checking on stage with the iPad and want to pick tracks to play.
Do you use a airport express as w-lan router? If so… you can use the built in mini jack at the Airport Express and plug it into the chinch-stereo input of the GLD-80. Now on your iPad you can choose airport express as your speaker-output!
(I know it’s not the USB, but this is a possible solution!)
USB Play/Rec control for editor would be cool, too.