[Greyhound]

Boozehound. I have been on a similar point and shoot journey. Just recently did a two inputs thru my interface into GarageBand on my Mac. Tweak sound to taste and then simply went live out of the headphone jack of the Mac into an iRig into the phone. My new iPhone shoots very good video and the audio is good to my ears. Add a little lighting to up the visual appeal. One important note...you need to be in the camera/video mode before you plug the iRig into the phone...otherwise it will default to the onboard mic on the phone.
Last but not least...I’ve done some simple iPhone videos using the iPhone mic in a nice sounding space and they came out pretty good...people ask...what setup are you using and are surprised to hear it’s just a raw phone video. Have fun!