Just upgraded to Windows 10 (build 10586).
Have ATI/AMD SB600 – High Definition Audio Controller [High Definition Audio Codec: VIA VT1708S Driver: VIA Technologies, Inc. | VIA HD Audio(Win 10) | v.6.0.11.1100 | 02-Dec-2015]
and
ATI/AMD RS780(M) Chipset – High Definition Audio Controller [High Definition Audio Codec: ATi RS690 HDMI Driver: Microsoft | High Definition Audio Device | v.10.0.10586.0 | 28-Oct-2015] audio devices and drivers.
Everything works fine using any system tool that tests audio (set up as front and rear speakers); all speakers produce sound in tests. However, there is no sound from the rear (surround) speakers for any application. Speaker Fill is selected (or unselected – actually doesn’t matter), no sound from rear. How can this be fixed?