Thanks for your comment.
I tried to modify and tested with that circuit.
It works, but the current is increased a lot!
Normally, current of our device is about 30mA, but it is increased to 130mA after modification.
The differences are only ground connection and 220uF capacitor for output. The others are same completely.
In this situation, as I disconnected the ground connection between mic & monoout, the current is decreased to normal range, 30mA.
Is this normal?
If more current consumption is not avoidable, we can't use 4 lines method.
I'm looking forward to your advice.