I use Sony Z1 Compact with the latest Android available (4.4.2).
There is a problem that the recorded voice of another person is too quiet in incoming calls. This problem happens in incoming calls only; both sides are recorded with excellent quality in outgoing calls.
I tried different audio sources besides VOICE_CALL and it didn't help. I changed voice recording formats (3GP, AMR, WAV) and found no difference. Noise Suppression is disabled on my phone.
I removed ACR and tried another application (Automatic Call Recorder, https://play.google.com/store/apps/details?id=com.appstar.callrecorder). It has "Increase recording volume" checkbox and I checked. Both sides' voices are recorded well so I believe the problem is not in the phone itself. However I like ACR and would prefer to use it!
Appreciate your help.