Yes, as a wild guess, putting 100ohm or 1000ohm resistors in series with each lead might make it safe for inputs and outputs, whether wired correctly or incorre

Yes, as a wild guess, putting 100ohm or 1000ohm resistors in series with each lead might make it safe for inputs and outputs, whether wired correctly or incorrectly. There is no need to keep low impedance to drive a speaker or headphone.