1

E6 should require root to boost volume from answer side. Caller voice is ok. But I can hear ok answer voice. But volume balance between answering and me is quite big. Is there any way to reduce volume of caller? Then I could boost volume of answer side with an app. I don't want to root phone because of updates.

2

If your voice is good but the voice of your friend is weak in recordings, you should root the phone then Boldbeast Recorder can fix it. Without root there is no solution on the whole market unfortunately.