Is It Just My Imagination?

I recently bought an Anthem D2V Statement pre-pro and am running it with a Monolinth 7-channel amp in a HT-only system. I plan to run the ARC EQ program in about 2 weeks, but have noticed what seems to be a big fluctuation in center-channel volume that seems to be random. I am a big believer in the KISS method, so I am not using any of the many EQ options available on the D2V. I don't have the Dolby volume EQ setting engaged, but I'm thinking there has to be a reason for this volume fluctuation. It's almost like the volume knob is being turned up/down, and I know it's not the amp because I was using a Marantz AV-8801 pre-pro before the D2V, and everything was fine. I would appreciate any thoughts on this from current or past Statement owners (or anyone else that might have a clue). I really love the sound of D2V, but this anomaly is driving me nuts.