\rTechnically you do not need a bass knob, but we definitely recommend them. When you add a bass knob to your subwoofer amplifier, you can quickly and easily control the subwoofer level to dial in the subwoofer output to your preference. No two songs are recorded exactly the same. You might be listening to some classic rock which has little to no bass in the recording. If you have a bass knob, you can turn the bass up to enhance the overall sound quality. If your have your music on shuffle, the next song could be some 80's or some hip-hop which has significantly more bass, or maybe even too much bass. The bass knob would let you turn down the subwoofer output to ensure that your music not only sounds great, but you also help minimize distortion. Adding the bass knob to your subwoofer amplifier helps extend the life of both your amplifier and subwoofer while also creating a more enjoyable listening experience.\r