For low impedance mic-to-high impedance aircraft, another option would be the impedance adapter from Pilot Communications USA. They have them in various connectorizations. Example:
https://www.pilot-usa.com/adapters/h...rs/pa-88h.html
They also have high-to-low, which I've personally used with a DC ONE X on a UH-60, but high-to-low requires a battery and you will go through a 9V battery every day.