As others mentioned bass extension. The speakers should be placed about 8-10 inches away from the wall. The passive radiator works off the wall. Too far out and you cancel the passive. Congrats on your upcoming purchase. I am a Klipsch owner for 33 years, owned the forte II for 29 years, and forte IV owner the last few years. You are making a great choice, any forte series is hard to beat, and INMHO the best overall value in the Heritage line. Spend some time with them before any updates. Placement is everything with the forte.