r/windows: https://www.reddit.com/r/windows/comments/10ff15p/solved_disable_switching_default_audio_device/ r/VoiceMeeter: https://www.reddit.com/r/VoiceMeeter/comments/10fm3cr/solved_disable_switching_default_audio_device/

SetDefaulDeviceOnConnection.xml

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <RegistrationInfo>
    <Date>2023-01-18T18:19:11.4118961</Date>
    <Author>NULL234\null234</Author>
    <URI>\SetDefaulDeviceOnConnection</URI>
    <Description>Stop annoying windows! i want to decide what stadart playback device i use.</Description>
  </RegistrationInfo>
  <Triggers>
    <EventTrigger>
      <Enabled>true</Enabled>
      <Subscription>&lt;QueryList&gt;&lt;Query Id="0" Path="Microsoft-Windows-DriverFrameworks-UserMode/Operational"&gt;&lt;Select Path="Microsoft-Windows-DriverFrameworks-UserMode/Operational"&gt;*[System[(Level=1  or Level=2 or Level=3 or Level=4 or Level=0 or Level=5)]]&lt;/Select&gt;&lt;/Query&gt;&lt;/QueryList&gt;</Subscription>
    </EventTrigger>
  </Triggers>
  <Principals>
    <Principal id="Author">
      <UserId>S-1-5-21-2611742254-942843215-3789948414-1001</UserId>
      <LogonType>InteractiveToken</LogonType>
      <RunLevel>LeastPrivilege</RunLevel>
    </Principal>
  </Principals>
  <Settings>
    <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
    <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
    <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
    <AllowHardTerminate>true</AllowHardTerminate>
    <StartWhenAvailable>false</StartWhenAvailable>
    <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
    <IdleSettings>
      <StopOnIdleEnd>true</StopOnIdleEnd>
      <RestartOnIdle>false</RestartOnIdle>
    </IdleSettings>
    <AllowStartOnDemand>true</AllowStartOnDemand>
    <Enabled>true</Enabled>
    <Hidden>false</Hidden>
    <RunOnlyIfIdle>false</RunOnlyIfIdle>
    <WakeToRun>false</WakeToRun>
    <ExecutionTimeLimit>PT72H</ExecutionTimeLimit>
    <Priority>7</Priority>
  </Settings>
  <Actions Context="Author">
    <Exec>
      <Command>C:\Temp\SoundVolumeView.exe</Command>
      <Arguments>/SetDefault "VB-Audio VoiceMeeter VAIO\Device\VoiceMeeter Input\Render" 0</Arguments>
    </Exec>
    <Exec>
      <Command>C:\Temp\SoundVolumeView.exe</Command>
      <Arguments>/SetDefault "VB-Audio VoiceMeeter VAIO\Device\VoiceMeeter Input\Render" 1</Arguments>
    </Exec>
    <Exec>
      <Command>C:\Temp\SoundVolumeView.exe</Command>
      <Arguments>/SetDefault "VB-Audio VoiceMeeter VAIO\Device\VoiceMeeter Input\Render" 2</Arguments>
    </Exec>
  </Actions>
</Task>

For some reason both of these methods didn't work on my device, throws me an error number when attempting to create the task that I can't find anything about. If this happens to someone else one day, here's the two things I needed to change in the scheduled task creation window (Windows 10, up to date as of 13th March 2025):

1. Change user account to my own
2. Create new trigger

Begin task = On an event
Log = Microsoft-Windows-Audio/Operational
Source = Audio
Event ID = 65

If this also doesn't work for some reason, you can hopefully find the necessary information in the Event Viewer under a path that looks similar to this: Applications and Services Logs > Microsoft > Windows > Audio > Operational. Here you should find an event every time an audio device is connected or disconnected.