Well, you don't want to duplicate the dimensions. The length vs the width vs the height should all be different. Most people put their speakers in front of a short wall. Some people will tell you a long wall is better. Those that do must have very large rooms cause in most rooms you'd be sitting awfully close to your speakers or with little room behind them or behind you, maybe both, and that's not good. Your speakers should be out from the corners and away from the walls but not by the same distance. You should sit between them at the apex of an equilateral or equidistant triangle with the speakers toed in more or less. Toe in is subjective. But, you were asking about the room. Besides, you probably already know that stuff. I say a rectangular room is best with speakers in front of a short wall and as little bulky furnishings in your listening space as is possible. That's my story and I'm sticking to it.