I've had some issues on my i9505 after the 4.3 stock OTA upgrade, but my big problem was that the USB port didn't work. Now I've fixed that, I installed Echoe ROM, first 14.1 before reading about the faulty Wi-Fi and now with "The Final Bean" with Wifi working on that one as I have to old bootloader.
Sound hasn't worked on either. I've heard this is a modem firmware problem, so I've tried a couple of the newer modem firmwares, but hasn't fixed anything. Here are my *#1234# stats:
Big thanks for any help!