It sounds like there’s a little motorcycle riding around in my earbuds. The frequency changes with the brightness of the screen. I play 100% with headphones so I have to return it, but if they all (or a significant percentage) of OLED units have this problem then I’ll just return it and not get another one right now.

Edit: it’s good to hear that not everyone has this problem. I’d be curious for those people who aren’t having the problem to test with a bright white screen. Mine gets worse as the brightness of the screen increases.

Edit 2: I used a MillSO 1/4” to 3.5mm adapter and my Sennheiser HD558s and I can’t hear the buzzing like I can with my Apple earbuds.