i haven't tested this, but i think it is a less bad idea for what i want to use it for, which is 5-volt power at up to 500 milliwatts, than for the ts80 tip. if the ts80 tip is 4.5Ω it needs to carry 3.8 amps, which means 17 volts, which would definitely kill your earphones. but you could imagine that the ts80 uses foldback current limiting or some more elaborate scheme to handle short circuits, which will happen in any case during hotplugging due to the shape of the 3.5mm plug. foldback wouldn't help (the earspeakers are higher resistance than the soldering tip, not lower) but you could design the iron to only turn on the 17 volts if 100 millivolts delivers 20 milliamps or more, say
and, yeah, square. i want to do higher data rates and simpler electronics than an actual audio interface can handle, though
