I need to mount my surround speakers (7.1 setup), and prefer to ceiling mount them. Since I have vaulted ceilings, I'll need to extend the speakers down on a pole, and each pole will have to be a different length. Any advice on where to find a mounting system? Or brands/etc? I don't know where to start looking. (edit: my surround speakers are light. Just a couple pounds a piece) Also, for speaker placement, I found this diagram at Crutchfield: Is this about right? Thank you.