I've noticed on two Tours now that out of the box the incoming call audio is fairly clear but low in terms of volume.
Forcing call volume to 100%, under options, seemed to fix the volume issue but it introduced some slight "distortion/static" on incoming audio. While testing various settings I also noticed that if I lower the volume during a call via the side buttons that the "distortion/static" decreases. Go figure... the out of the box volume is about the same volume. Interesting.
For me the trick evidently was "Boost Treble." I'm not sure why I need to enable this to remove the "distortion/static" at 100% volume but it worked. I hope it helps someone else in a similar situation. Good luck.
