High Frequency Whine.
Ok, so the screen had some stuck pixels and a horrible whine... This was a replacement screen for a previous bad one with dark clouding... Well they replaced it alright, and scratched my case and foot in the process, which was also replaced after some phone work. Everything seemed okay... high frequency whine is gone, no more stuck pixels, new case... till I discovered a new issue... My computer now has this weird pop static issue in the left speaker. Almost like a walking talking keying up after a sound plays, this continues for 20-30 seconds every time. If i use my duet, it doesn't happen, and the same goes for headphones. I'm at my whits end.
Second iMac, third screen, second case, third foot... Give me a new one already! You sold me a Lemon!