Is there any general rule of thumb for the ideal placement for a 5.1 HT setup? I have a room where I can place my speakers up to 15' deep x 11' wide, and need to know if there's any general rule for where to position them for ideal impact.

* Is it proportional to room size?
* Does ceiling height have any impact? (cathederal ceiling in my LR is about 12' high)
* Toe in / angling rules of thumb?

Obviously, the placement of furniture, and it's construction (absorbtion / reflection) will play a part in the fine tuning, but I'm looking for a recommended starting point.

Thanks in advance.
u