I got the Anthem mrx720 two days ago, in a few days I'll do the arc room correction. So far I'm extremely happy with the sound.
I noticed the dialog is clearer than before, I use a JL audio F113 subwoofer,
I never heard my sub as tight and powerful as this, that's a welcome improvement.
Still messing with it for the moment, I'll post about the room correction later.
I take nothing away from the Arcam av400 sounds great, loved it, its just a little warmer than the Anthem and my speakers really loved the Anthem.