vMix Call provides three different audio feed options that can be sent to all guests.
All three include built in automatic mix minus, so regardless of the option selected the guest microphone audio will not be returned back to them.
This is the default and simplest option where the guest will hear the same audio as the stream and recording, minus their microphone.
This option will allow the guest to hear everything the vMix operator hears, minus their microphone.
This allows the vMix operator to Solo any audio sources in the audio mixer they want the guest to hear without being heard on the recoding or stream.
This is useful for Talkback scenarios where a producer's microphone and guests are muted with solo turned on, creating a private conversation
between the producer's and guests that the audience can't hear until they are unmuted.
vMix provides seven independent audio mixes / buses in addition to Master and Headphones which can be controlled using the A and B toggle buttons
underneath each audio input in vMix. (right click these buttons to see Bus C-G) For more information see the Audio Buses section of Audio Mixer.
These separate audio buses allow full flexibility when configuring guests audio in advanced production scenarios.
For example, a "virtual green room" could be created whereby any waiting guests can be turned on in Bus A to talk amongst themselves
with the M or Master being turned on just before they go on air.
When using this option, be sure to enable any sources before hand you wish the guests to hear such as the interviewer's microphone and any video clips
they might need to hear as well.