"Been there, done that". I checked levels tab in speaker's properties, i have only one volume slider.
Most people probably just can't hear that static sound because they don't have such sensitive ears or don't play movies/music on laptop.
Sound driver works properly on Windows 7, 8, 8.1. Only Windows 10 has problems with (and not only) it (Optimus stuttering).
It is an absurd that every new device (Intel 7th gen processors) is "compatible" with Windows 10 only (I don't mention Linux), but it actually doesn't work properly on these devices (Creators Fall Update broken so many things). That's not right. I started considering installing Linux (which also has no issue with sound on this machine). Isn't Dell supposed to contact Microsoft and try to solve these problems (since these are Microsoft fault especially)?
Also, I hope for Dell to release some tools for fans speed configuration. Coolling on Inspiron 7577 is great, but way too aggressive.