Not really defending it. Just stating my experiences and trying to offer solutions.
There seems to be a theme in this discussion that it is mainly the sound from the usb that is the worst, hence my suggestion as it also used the optical.
Having said that, i have a racing buddy who recently bought the steel series arctis 7 wireless headset which is connected via a wireless transmitter that only uses the ps4 usb. He says he had no volume issue either. That leads me to 3 possible conclusions:
1 we are not all experiencing the same issue, in the same way we are not all experiencing the blue screen of death post patch 4.
2 it IS hardware specific.
3 some of us are already deaf
If the truth is 1 then i would hope for a patch from sms but if it is 2 or 3 you might be waiting for a solution that never comes. Is that acceptable? Probably not, but it might be reality. So you have the choice to wait and see or find a workaround yourself.