how do i set output of submix voice in XAudio2? (metro)
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I tried using the SetOutputVoices function, and the constructor parameter, but both result in a XAUDIO2_E_INVALID_CALL as the result when used on a submix voice.

the docs say that you get that error by calling it from an audio callback, but i'm not. i have even tried calling it before starting the audio engine.

the same method works for source voices, so i'm pretty sure i'm not passing a bad XAUDIO2_VOICE_SENDS structure.