New PN59D8000 owner here as of about a week ago via Amazon Prime. I've got the same buzzing sound. The best I can describe it is, on-axis, it sounds like an electrostatic speaker where the volume's been cranked up really high but there's currently no input signal. It replaced a six year old Pioneer PDP-507CMX 50" plasma. Obviously the old set was a good four or five inches thick, but except less than a foot away from it where sound coming from the back radiated off the wall, it made no appreciable noise.
With this 59D8k, if I'm exactly in front of it, I can hear the noise at least back as far as 20 feet. Going off-axis it gets much quieter, whether to the sides or below vertical center. I find the noise incredibly annoying but I don't want go go sending it back without knowing if this is normal for current generation sets or not. Mine shows a manufactured date of Jan 2012 so I'd have hoped the bugs would have been worked out by now.
Is Best Buy going to have examples of this set I could go compare to or would the background noise of the store be too loud? I'd like to go listen, and if it's not noisy like mine, get it replaced.
Or should I just refund and get the Panasonic VT30? I really liked the 59" size of the Samsung but I could go up to 65" VT30 if I had to; 55" version would be smaller than I want.