VidBlasterX has two distinct audio systems built into its design: the legacy audio engine that is designed to route all audio to an external mixer and vice versa, and the new VBXA2 audio engine which is built around the Audio Mixer module. VBXA2 is a new audio system that brings the same flexibility to audio routing that you are already used to for video. VBXA2 offers high quality, low latency audio mixing and routing. Audio can be ingested from internal modules or external devices, mixed, and output to modules like the Recorder and Streamer while monitored on an external audio device.
Although you can use both the legacy audio system and VBXA2 at the same time, typically you'll be using just one.
Using the legacy audio system
All modules that generate audio, like the Player module, have an Audio Output option in their popup menu where you can select to which external audio device you wish to route audio. This usually is part of an external audio mixer, or connected to it. Modules that ingest audio, like Recorder, have an Audio Source menu entry where you can select from which external device audio needs to be taken. Typically this is the output of an external audio mixer, or a sound card to which it is connected.
As audio from modules will be directly ingested by the Audio Mixer module, all modules that generate audio should not send their audio to external devices. This can be achieved by selecting Audio Output > No sound. The module is then selected in the Audio Mixer module. Modules that ingest audio will select the mixer as source, e.g. Audio Source > Audio Mixer 1.