[Bug 39321] New: Unrest doesn't play audio with built-in Xaudio2 (needs xaudio2_7)

https://bugs.winehq.org/show_bug.cgi?id=39321

Bug ID: 39321
           Summary: Unrest doesn't play audio with built-in Xaudio2 (needs
                    xaudio2_7)
           Product: Wine
           Version: 1.7.51
          Hardware: x86
               URL: http://store.steampowered.com/app/292400
                OS: Linux
            Status: NEW
          Keywords: download
          Severity: normal
          Priority: P2
         Component: xaudio2
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail]
      Distribution: ---

The game runs without audio, installing native xaudio2_7.dll (winetricks
xact_jun2010) works around the problem.
Plain terminal output doesn't show anything related.

Can be reproduced with Unrest demo on Steam.

System Shock:Enhanced Edition from gog.com also has this problem (sound
effects, voices are missing, cutscene is playing without audio).Only in-game
music works, because music is played through midi (needs timidity).

FWIW, both games played audio with built-in xaudio until

commit 7a23b9f0f85f652c8d01a0296455e07322268dac
Author: Andrew Eikum 
Date:   Thu Aug 20 15:02:52 2015 -0500

xaudio2: Implement IXAudio27::Initialize.

Not sure if this is the same as bug #39021: AFAIK, audio has never worked in
Valkyria without native xaudio2.

wine-1.7.51-201-g60d1d6f
Fedora 22 32-bit
Alsa 1.0.29 (pulseaudio is not running)
Openal-soft 1.16.0

~/.alsoftrc contains:
drivers = alsa