We use LM833 to design the mic pre-amp as 'Single-Supply, Electret Microphone Preamplifier Reference Design' recommended,then the audio input(called device1) transmit to another device(called device2) which is the same design.
We can play normal audio from device2 output,but we also find same small signal from device1 output which can be heard when plugging in headphone.It's a serious problem.
We surmise the signal couple through GND,but don't know how to resolve it.
Do you have some suggestions about audio input & output isolation？
Thanks a lot!