For the four π speakers, I like to position them far enough apart I can cross the forward axis in front of the listening position slightly. That's one reason why the π cornerhorn arrangement is so good - when you put them in the corners, they tend to do that automatically. This makes stereo imaging nice in a large area.This positioning arrangement does not apply to two π speakers. In that case, it is generally best to be less than 30o off axis horizontally from both speakers, with the angles equal. You should also strive to be on the vertical axis with the midwoofer. The sweet spot is smaller, and defined by a line where both these conditions are met. That's where they sound best.