Then you'd also need a +10V supply for the port's +5V input, and to convert logical levels for communication between them. That would be trickier than just ampl

Then you'd also need a +10V supply for the port's +5V input, and to convert logical levels for communication between them. That would be trickier than just amplifying them because low/high of 0V/5V would become 5V/10V. Constant voltage offsets are generally a real pain.