I am getting my Atlantic Technology 454e THX speaker set from Alan Gouger next week. I will use these with a Denon AVR 4800 and Denon POA-5200 2 channel amp. I will be using Atlantic Tech 370 INSR speakers ceiling mounted for the side channels and Atlantic Tech 454's for rear effects. Can anyone offer advice on where to place the ceiling speakers in relation to the "sweet spot"? I have no choice, I have to use ceiling speakers.