trrs cables are notoriously undependable imho. Getting the right signal to the right ring is a challenge. At the very least you can’t route stereo rca to the mic input part of the trrs connector, as the mic is - by default - a mono source.
So for streaming purposes … well … not the best option. I have also found that if you use the lighting to mini-jack adapter (as modern iPhones don’t have mini-jacks anymore) this can add an extra layer of potential trouble. You’d expect it to behave like it was a hard-wired mini-jack, but a recent test with a dj splitter cable did not work as it was supposed to.
Have a look at this thread, in particular the document I shared at the end of my reply. As a possible alternative (with much more potential other uses) for iRig or Griffin or such.