When I tried one a few years back it was standard 17 inch wide, because that was one of the changes from the 1506 which was 19 inch and so woudn't fit in a normal rack. It was about as deep as a Denon 5600 which is not overly deep, and was about 8 inches tall.
It will fit in a normal rack.
One more thing, Anthem wasn't around when I tried teh ATI, but I also tried the Rotel when I bought that ATi, and I found the ATI a completely higher class tehn Rotel in quality and it had incredible 3db of headroom, which is very rare for am amp in that class. They can be had for 1450 new on a good price, and have a 7 year warranty, and are completely modular so If a channel goes out, you call, give them a credit card deposit and they send you a new channel and then you send back the bad one, and then they give the credit back for the channel they loaned you in transit. If you liked Rotel are are thinking this is lower, I think you will be pleasantly surprised, and it is also very open and neutral on music, and I found this to be the best in that regard over like 6 other similar priced amps at the time.
All that said, it weights a whopping 73 pounds, feels even heavier then that for some odd reason. It doesn't get very hot either, but it is one of those that you have to turn the pre amp off first because it carriers so much fricken juice the speakers will continue to play for another 20 second after you turn it off.
