Question / Help Audio does not stream but does record - why?

Al Ches

New Member
I am trying to use OBS to live stream meetings and while the video stream is fine there is no audio, other than an occasional click or sharp pitched squeak.
The audio is coming from a public address amplifier, (several microphones and video playback from a laptop) using the amplifier's Recording Out socket. This feed is to the headphone jack of the second laptop (with OBS installed). The headphone jack is configured as an Aux Line In.

My immediate assumption was that the output of the amplifier was not compatible with the input to the laptop, or the cable was no good, but the audio mixer on OBS modulates properly in time with the microphones and video sound from the amplifier and OBS records both sound and video just fine.
The fact that OBS records the audio OK, seems to say that the Aux Line In feed is OK but that there is something wrong with the audio streaming settings in OBS, (maybe wrong audio channel set somewhere), but I cant find it.

Can anyone help please?