The height, width and depth are in the wrong order. As you look at the front of the speaker the true dimensions are Height- 400mm, width- 460mm, depth- 520mm. So, the depth is the longest measurement meaning it will stick out into the room more.
Apart from this, absolutely amazing subwoofer. Incredibly powerful, clear sound, and a bargain for what you get. If you need an active subwoofer, definitely get this one!