Audio Research DS Series Amplifier owners. Turn on "twang" from transformer?

Just got a brand new DS450 and I'm burning it in now. I notice when it relays on, there is a fairly audible twangy electrical sound that comes from it that subsides after a couple of seconds. None of my other amps have had this type of sound after the relay clicks on.  Has anyone else noticed this? I can only notice it if there is nothing playing and the room is silent, if there is music flowing from the preamp before the amp relays on. I can't notice it.  Is this common?

Thanks!