There are different theories but rooms and tastes are different so it's tough to specify a correct placement. We suggest you experiment with different locations to see what works for you. As a general rule of thumb for the best sound stage balance, the speakers should be equi-distant from side walls and a different distance from rear walls. Our front-ported speakers (such as HD3) do not need any rear panel clearance for better bass but we recommend keeping them a few inches from the rear wall for adequate ventilation.