There is often a debate among users whether a power conditioner should be put at the top of the rack or at the bottom. Most people put them at the top of the rack due to the wires and cables that have to be put into the power conditioner. But, some of these power conditioners may create magnetic waves which may create disturbances in your AV equipment. So, those who face this audible issue, should place their power conditioners at the bottom of the rack!