buzzing noise on the Rotel 1067 please help..

I have purchased a Rotel 1067 7.1 channel surround from a fellow member here. The machine is amazing and practically new. The problem is that there is a buzzing noise coming from all of the speakers all the time. At the beginning I thought it was the ground issue. I have try using a different outlet, unplug everything except the speaker wires, using different ground wire set up and it was still there. I finally connected my Sony 5.1 100w per channel inexpensive receiver from Circuit City with the same exact set up and there was no noise at all. I took it to a famous dealer here in New York City and they set it up the way it should and was still making that constant zzzzzzzz noise( sound like a high current wire), they even took a new one out of the box and it was doing the same thing.
The tech guy at the dealer said that the noise was too excessive but no one has ever complaint about it. Called up Rotel and the tech guy there said it was suppose to be like that.
I am a concert cellist so I am very sensitive to buzzing noises but for a $2000 machine I think it would be less noisy than my $300 Sony right? The buzzing noise is loud enough from the 5 speakers that it gets on my nerve when I am trying to watch a movie or listen to music.
Does anyone out there has the similar problem?
Thanks