The sub should always be on the floor, and it can be either in front or behind you--it doesn't matter. The satellites seem to work best when they're 5 to 6 feet above the floor and positioned a bit behind you and off to the sides about 4 to 6 feet.

As for feedback, I have never experienced this problem since I began using high-quality, super-cardioid mics.

Happy Holidays,

Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!

K+E=W (Knowledge Plus Experience = Wisdom.)