You need to set the volume knob half course and the cutoff frequency full range on the sub-woofer. Then go into the amplifier settings to set the cutoff frequency close to the frequency advised in the manual. The position of the speaker in the room can have some importance and we recommend to try different position. Generally, if the sub-woofer is placed in a corner, you can feel an excess in the extreme-low frequencies. In this case, move it about 40cm away from the wall.