I was using Liberty rom before the official OTA update came out that apparently fixed some issues, like camera lag + headphone whine.
I flashed back to stock, installed the OTA, and everything was excellent. Camera worked a bit better, and the headphone whine was completely gone!
I decided to try out the th3ory rom, didn't install purity mod yet. I put on my headphones and noticed the whine was back. Did the rom install the old kernal or something? =[