I recently got my MBP back from an Apple Certified Service Centre where they replaced the logic board and IO board. They fixed the initial issue (unresponsive startup manager + slow boot), however now my left speaker is crackling and popping. This is in MacOS 10.11.6 (El Capitan).
What baffles me is that the speaker works perfectly fine in Windows 10. There is no distortion in the Mac startup chime either.
Things I've tried:
- Reset PRAM + SMC
- Reinstalling El Capitan and upgrading to Sierra
- Switched L+R in Audio MIDI setup
When it was working perfectly fine in Windows I was convinced that this was a software issue, however I had no issues before the repair. I was hoping that there's something I can do to fix it myself as I can't part with my computer for another two weeks for repair.