While Switcher Studio can pull multiple video sources into one broadcast, it will only record the audio from the main "switching" device that you use. In order to have a second audio source--whether through another recording device or via your computer using Switcher Cast--you will need the aid of a mixer. A basic mixer will work and can be purchased from many online stores.
Using the audio combo-jack on your iOS device, you can easily inject an auxiliary audio input into your production. To connect audio to the iOS device you are going to need an adapter to convert the input to TRRS. There are a number of adapters that could be used, but we recommend the iRig PRE by IK MultiMedia.
Use a "Mono" output from your PA or mixer. If nothing has been panned on your mixer, you could also just use the Left channel of the "Main Output". Often times, this output will be an XLR output. Connect the XLR cable from the mixer into the iRig. Make sure the iRig is turned ON. There is no need to use 48v power for a Line-Level signal from your mixer. 48v power is only used when an external Microphone requires what is called "Phantom Power". Now, plug the iRig into the combo jack on the main switching device. Next, open the Audio Tab and adjust the gain on the iRig to make sure you have a good audio level.
If your mixer has a 1/4 inch output or an RCA output, we recommend adapting it to an XLR connector. The iRig is a portable tool with an adjustable input gain. This is the simplest and most reliable way to inject auxiliary audio into your production.