Creek 4240SE has buzzing sound.

The buzzing will be the transformer and the common reason in this case is that the transformer was probably designed for UK power supply, but with a 120V primary tap for selling in the US. Very few manufacturers use a different transformer for the different mains supply. So being a British piece of gear the transformer is probably optimised for 50Hz operation, yet in the States you use 60Hz. Usually this does not present much of a problem and the situation is usually worse the other way around - because 60Hz operation is usually easier on a transformer than 50 Hz is. My local mains is 240V 50Hz, and my Theta Gen Va DAC buzzes badly because the transformer does not like working at 50Hz. But I would not fret about it unless the noise is intrusive, or the unit is getting unusually hot. I have found that using better isolation devices such as seismic sinks or BDR cones reduces the buzz markedly. You could also apply some damping directly to the transformer.

Sometimes power supply transformers, especially in amplifiers, buzz. I don't know of anything that will stop it, unless one of those new PS Audio units might. Those might limit current too much for an amplifier, though...