Shutting off amp noise

When I turn off my poweramp (bel canto evo2), there is a small noise through the speaker, even though the preamp is on. Is this indicative of a problem? My other amp (rotel) doesn't do that.
Is it through both channels? And is it a slight buzzing (similar to a fruit fly) that fades in about 5 seconds or less?
The Rotel is an analog amp and the Bel Canto is digital. Since some digital amps are succeptable to RFI interference like the Nuforce for example, you might try relocating it or plugging into a different outlet. Do you have a tuner very close to the Bel Canto?
No its a soft pop, like if you turn off the preamp before the amp.
I think it could be my (loose) rca connectors, one of them created a buzzing noise when loose.