If we have a Leitner corded with low mic audio we want to make sure the settings are set to 2 & 3. Some may come on 2 & 4 and will work, but we noticed it works best on 2 & 3.
Try moving the compat switches with a paper click or ball point pen. (located on the cord right where it connects into the other cord)
If this does not work, you may need an amp. The amp will allow you to adjust both their listening and microphone audio.