New member, first time poster, but I've referenced this forum many times and wanted to contribute on this topic.
I got my new Sammy 3 weeks ago, and immediately noticed the buzz from my primary viewing position at 12 ft! It's highly directional, concentrated directly in front of the screen, even at 12 ft. If I move off-axis 10 degrees to either side or up/down, the noise is cut in half. Adjusting brightness, contrast, or cell lighting doesn't seem to have any effect. I need to turn the volume up to 12-15 to drown it out (2x normal listening level), and even then, during quieter moments of programming it's clearly there!
So, last weekend I emailed Samsung from their website. Within a couple days they responded and recommended I submit a service request for technical diagnosis. I did this and received a phone call from a nearby shop, who scheduled an appointment for the following day. They even called Samsung, and at their recommendation had a replacement power supply board sent overnight! They showed up on time, and said they've never heard a TV buzz like this before... and they sell Samsung. Hmmmm. Anyway, the older fella couldn't hear it very well, but the 20-something agreed it was clear to him.
Since the power supply is located at top-center behind the panel, and the sound seemed to be strongest in that area, they decided to replace the supply (15 minute job). But, as others have reported, it did NOT help.
I really like the TV otherwise, and my wife can't hear the buzz nearly as well as I do. And, since I really don't want the hassle of returning it to an online retailer, I'll probably live/suffer with it. If I angle it slightly away from me, and prop the rear of the stand about 1/2" (to angle the panel downward), it cuts most of the noise from my viewing position. Yeah, I know this is ridiculous. It's also absurd that Samsung hasn't addressed this defect in their products, after years of complaints!
In closing... Initial response from Samsung and the authorized technician were excellent. But, that provides little solice when the problem has no known fix. I wish I'd visited this forum before buying my TV. Had I known how common this problem was, I wouldn't have gambled with Samsung.