https://bugs.winehq.org/show_bug.cgi?id=51921
--- Comment #7 from Rémi Bernon rbernon@codeweavers.com --- Sure, but then it's actually pretty much an Unreal Engine bug, as they should use this API the way it's supposed to be, and not trigger assertions.
From the Unreal Engine source I can see that they check the audio device
properties to get the initial channel mask, but then hardcode the number of DSP settings channels to 6, regardless of how many channels were specified at initialization.
I also checked with debug native DLL from the DirectX SDK that this assertion is genuine, and an exception is raised (and explicit debugstr messages printed), so all Unreal Engine games would also fail here.
I think the only correct thing to do here is to build Wine FAudio with assertions disabled, and that would restore the original behavior.