I've started getting an issue lately where I sometimes can't hear the sound of my gun firing while there are some other noises going on in the background. It's especially noticeable when I fire at the same time as my enemy does.
Those are my audio settings:
dsp_enhance_stereo 0
dsp_slow_cpu 0
snd_async_fullyasync 1
snd_pitchquality 1
snd_spatialize_roundrobin 1
snd_mixahead 0.05
snd_mix_async 1