passed 100Hz. When you turn the sub fq all the way up it bypasses its filter. some subs have a switch for that. Let the avr do the filtering. You dont want to have 2 filters overlapping each other. If you set your speakers to small they will sound the best because of the signal sent to them and the sub will get all fq below 80 hz if that is what you set the avr crossover to. let the sub handle all the bass because it will sound better and dont set the crossover too high on the avr because then you will start to get unwanted sounds and maybe some dialog sent to the sub.