I'm not sure if the timing of root was just a coincidence or not. It has Android 4.2.2; Build number is JDQ39.I337UCUAMDL.
Could rooting have done anything to affect the audio?
Is there anything I can try to fix it?
I've been using an 18 ohm Klipsch headset for a long time on my S4, but recently after rooting it, I started getting the crackling audio issue. I've confirmed that the headset still works fine on other devices and it worked fine before on my S4. I tried another 18 ohm headset and it has the same problem. Cheap headphones don't have the problem.... go figure...