Tiny click with my Krell


Setup

Anthem MRX500 (preamp only, 2 channels, unbalanced)
AppleTV
Oppo BD103
Krell KSA 150
Cornscala Speaker

I ran this setup for several years but without the Krell.  In its place was a Hafler 9303 Transnova.  I replaced the amp a couple of weeks ago, and the first thing I noticed was this tiny clicking that happened during playback of video.  Its subtle, describing it as a pop is too much, more like a tiny pop or click.  It happens when I move through the menu with the remote.  It also happens during playback during a scene change or an audio change.  For example, last night I streamed Humans and when a scene changes there is a click.  Or within a scene, lets say when music is playing and then stops for dialog, again there is this tiny click.  Can anyone explain to me what is causing this?
pondracer