its also possible that it acts like a power source if the adapter is non existent

spelling error
the manual says "service port"
I'm not sure what it means, but I don't think you can do anything usefull with it
USB port on the back of the PolyTune


The USB port on the back of the PolyTune - what is that used for?


The USB port on the back has no end-user applications. It is solely intended for service access to the unit.

From the TC Electronic FAQ Knowledge Base
Quote by Vendetta V
^^ lol i've got a similar question.. RP355 by Digitech seems to have midi or something but it is not in the manual.. but when i hook it up to my PC it says midi interface is installed and blah... wtf?

Are you sure those arent XLR outputs? Mine has two of those, and a mini usb thing.