Same EXACT Problem
Not that this helps you at all, but I have the same exact problem. I have tried most of the same "solutions" you have tried as well, also to no avail. I have tried countless ROMs, reboots, Odin flashes, etc. What gets me is that once in a while, after installing a ROM or using Odin to go back to stock, I'll get my call audio back for a day or two. Eventually, and without apparent reason, the call audio goes away, and I'm back where I started.
In fact, I was about to write my own XDA post, but then I saw yours, and figured it would suffice.
Good luck. I hope someone has a solution out there because I'm at my wit's end.
Correction: All the same except that my phone is actually a MetroPCS SGH-M919N. Supposedly its the exact same model as the i9505.