After we published our review of the Samsung B850 series several users have reported problems with annoying buzzing. It now seems that the problem has been resolved by Samsung.
A user in our forums has reported that Samsung has now resolved the buzzing issues on the B850 / B860 plasma-TV. The buzzing is not caused by the power supply, like first assumed, but from the plastic on the back of the screen that is too thin causing it to resonance. The buzzing can be resolved by adding small rubber thingies on the back of the TV.

Samsung B850
If you have buzzing issues try contacting Samsung. In Denmark the issues have been resolved on previous as well as new sets.