in my experience, if your surrounds are satellites (mainly high frequency) with small drivers they tend to be very directional because of how small drivers tend to "focus" much thinner "beams" of sound in the high range. this usually happens to me whenever i use speakers smaller then 6 inches. think of it like a flashlight, the smaller the flashlights end is the less area of intensity the light has. another common misconception is that surround left and rights are supposed to go directly behind you, this is not true nor is it ideal. they should either be direct to your left and right of the listening point or slightly angled to the left back and right back, but not directly behind as you have your fronts directly in front of you, the only way putting speakers directly behind you is useful is in a 7.1 system, and even then i myself prefer to use a single back channel (6.1) using a center channel, this is because of the way a center channel speaker is designed is to make a much wider area of coverage. in my experience speakers sound best placed about 2 feet above the sitting ear level, this works best for both standing and sitting.
again im not using any technical knowledge on this, just from what i have experienced myself.
