Using the same audio input on multiple devices, recording iOS video I am recording video with two iOS devices (which I will then use for camera cuts, etc...), and I would like to use a single audio source for both videos.

My thought is that I would need some kind of splitter that could take output from something like the iRig PRE, then split that and plug it into both devices as a microphone and it would work as such.

Is there such a device?

Or am I going about trying to edit video from multiple cameras all wrong?

(What I'm doing at the moment is recording the audio line separately, then syncing it to each video, rendering out intermediate sync'd up video, and then editing those files together, which seems like it wastes an extra step; but I've no professional training in how this is generally accomplished.)

The only answers I've found here seem to involve using separate headphones and a mic running into the same jack on a device, which is kind of the inverse of what I am looking for.
There were no devices which were designed to filter matching audio into two iOS devices at the same time. The solution I went with in my comment is likely the best.

That is, Adobe Premiere and Final Cut Pro X both have a feature which will use audio to automatically sync up video tracks. I recorded high quality audio with an external microphone, and using that in conjunction with the audio built into each device, FCP:X was able to create a multi-camera clip with the three audio tracks and two video tracks synced up. I could then select each audio track and each video track independently.