Comment # 2 on bug 1048356 from Sunito Suska

That helped!

Thanks a lot for suggesting to try the 4.12 kernel and the explanation
that older kernels cannot deal with Kaby Lake properly.

I've installed it via the Kernel:stable repository and 
audio works like a charm now! (However, if the system is
in "state 3" already, booting with kernel 4.12 will not 
get the machine out of this state, only the complete 
powerdown will help.)

There also is a downside of 4.12 for me: Virtualbox does not
work ... yet ... perhaps I'll get that sorted out.