depends on the kind of bass knob and if you set your gains properly. Some bass knobs are centered around a specific frequency ex 45hz. So when you turn up the knob, you are not turning up all bass, just boosting that one area. Others boost the gain of the amp, so all frequencies that are going to the sub. In both cases you want them to be at full when you set the gains and then turn them down when you want less bass. If you have them low when you set your gain, then try to get more bass out of your system from the knob, you will just be clipping your amp.