no sound in MURI (267360)

edit: system info: https://gist.github.com/Cuddlypuff/a518019d119623d9a1b7552e284c1f6d

relevant snippets from steam-267360.log:

158787.217:0029:002a:trace:module:load_builtin_callback loaded dmloader.dll 0x171020 0x7d180000
158787.217:0029:002a:trace:module:load_dll Loaded module L"C:\windows\system32\dmloader.dll" (builtin) at 0x7d180000
158787.217:0029:002a:trace:module:process_attach (L"dmloader.dll",(nil)) - START
158787.217:0029:002a:trace:module:MODULE_InitDLL (0x7d180000 L"dmloader.dll",PROCESS_ATTACH,(nil)) - CALL
158787.217:0029:002a:trace:module:MODULE_InitDLL (0x7d180000,PROCESS_ATTACH,(nil)) - RETURN 1
158787.217:0029:002a:trace:module:process_attach (L"dmloader.dll",(nil)) - END
158787.217:0029:002a:err:dmloader:IDirectMusicLoaderImpl_SetObject : could not attach stream to file L"C:\windows\system32\drivers\gm.dls", make sure it exists
158787.217:0029:002a:trace:module:load_dll looking for L"C:\windows\system32\dmusic.dll" in L"C:\windows\system32;C:\Program Files (x86)\Steam;C:\windows\system32;C:\windows\system;C:\windows;.;C:\windows\system32;C:\windows;C:\windows\system32\wbem"
158787.217:0029:002a:trace:module:get_load_order looking for L"C:\windows\system32\dmusic.dll"
158787.217:0029:002a:trace:module:get_load_order got hardcoded default for L"dmusic.dll"
158787.217:0029:002a:trace:module:load_dll L"C:\windows\system32\dmusic.dll" is a fake Wine dll
158787.217:0029:002a:trace:module:load_builtin_dll Trying built-in L"dmusic.dll"
(...)
158787.323:0029:002a:trace:module:load_builtin_callback loaded midimap.dll 0x4551580 0x7c850000
158787.323:0029:002a:trace:module:load_dll Loaded module L"C:\windows\system32\midimap.dll" (builtin) at 0x7c850000
158787.323:0029:002a:trace:module:process_attach (L"midimap.dll",(nil)) - START
158787.323:0029:002a:trace:module:MODULE_InitDLL (0x7c850000 L"midimap.dll",PROCESS_ATTACH,(nil)) - CALL
158787.323:0029:002a:trace:module:MODULE_InitDLL (0x7c850000,PROCESS_ATTACH,(nil)) - RETURN 1
158787.323:0029:002a:trace:module:process_attach (L"midimap.dll",(nil)) - END
158787.323:0029:002a:err:winediag:MIDIMAP_drvOpen No software synthesizer midi port found, Midi sound output probably won't work.
158787.323:0029:002a:trace:module:load_dll looking for L"C:\windows\system32\dmsynth.dll" in L"C:\windows\system32;C:\Program Files (x86)\Steam;C:\windows\system32;C:\windows\system;C:\windows;.;C:\windows\system32;C:\windows;C:\windows\system32\wbem"
158787.323:0029:002a:trace:module:get_load_order looking for L"C:\windows\system32\dmsynth.dll"
158787.323:0029:002a:trace:module:get_load_order got hardcoded default for L"dmsynth.dll"
158787.323:0029:002a:trace:module:load_dll L"C:\windows\system32\dmsynth.dll" is a fake Wine dll
158787.323:0029:002a:trace:module:load_builtin_dll Trying built-in L"dmsynth.dll"

Start with the linked system information and the steam-267360.log excerpts, focusing on dmloader.dll, dmusic.dll, midimap.dll, and dmsynth.dll. Reproduce MURI (267360) under Proton and determine whether the missing gm.dls or software-synthesizer message accounts for the missing sound; done means the game produces sound without those reported failures.