A brzzzzz noise from transformer, is it normal?

Hello audiophiles,

I need help on this brzzzz noise from my Classe CA201 amp, properly from the transformer. I could hear its sound like a small power plant when I put my ears close by (even I disconected all sources, so there is no signal feed to it), it is quite bother a bit, especially on a quiet day when music stop. Is this noise normal for a big amp or any amp? The good thing is the noise does not go to or sound on the speakers. Or is it because of the dirty power I feed it. I did try to turn off everything such as lights, air conditioning etc... It sounds quieter a bit when the amp heat up.

If you have the same problem, or know what this noise come in from or how to fix it, please post your help. I don't want to send the amp to manufacture if it is really a problem. This amp is 70lbs piece of rock not a pleasure thing to ship around.

Thanks all for your help.