I want to connect two MIDI keyboards by connecting the MIDI OUT of the first keyboard to the MIDI IN of the second keyboard, but I don't have the connector and I'm nowhere near a music store to buy one. And for that, I want to make my own DIN to DIN MIDI connector. I have two male 5 pin DIN connectors, and the question is, do I have to put some kind of isolation (usually an optocoupler) between the connectors? Or is it safe to just solder them directly without some form of isolation? As far as I know, optocoupler isolation usually found in MIDI to USB interface/adapter. I don't know if a MIDI to MIDI connector is supposed to be electrically isolated or not.