With the 5.1 headset I`m using to play ARMA3 with, I experience deaf-spots from each of both front directions, approximatly 30-45° from center-front to right and left side. This angle varies slightly between 1st and 3rd person view.
(I strongly believe this is because my headset`s internal speaker alignement, more info in "additional inforamtion" section)
I wish for surroundspeaker position adjustment capability in ARMA3 configfiles, like CS:GO does it with the
"snd_front_surround_speaker_position" and "snd_rear_surround_speaker_position"
commands.
(I was able to fix the deaf-spots in cs:go by using a lower frontsurround speakerposition value)