You've probably seen some of the reports from others regarding sound issues on the z170 based boards. Some attributed to drivers, some related to software.
If I had to guess, low volume static sound is related to drivers, but other things like:
Improperly mounted board, over tightened screws
Power coming from a "dirty" or improperly grounded source
and some 3rd party headphones, speakers or powered USB hubs or devices can also cause problems
Also cheap audio cables and dirty/dusty contacts can cause static
Again, not saying these are you. Hard to do much more than speculate about this here in a forum.
Trying using chipset and audio drivers from the same time frame together. Uninstall any manufacturer specific control Panels and go with MS HD audio.
