The sub level on your HU should be atleaste 3/4th of the way up, if u have a bass knob put it at max. Then all control will be in bass knob and it will be more sensitive. Also ive heard planet audio bass knobs dont work very well, read alot of reviews saying that.
If u have your HU sub level at 0 its puttin out like .02v's lol when it should be 2v's (or w/e ure HU is) Its not a bass boost, it s a voltage potentiometer. Your also robbing yourself out of a HUGE amount of power by having it that low. With my alpine sub level at 0, i could get the amp to put out 300watts(AP APSM-1300) and it was rated for 1000 @ 1ohm. Put my sub level at 12 out of 15 and it was pushing 750rms with my gain extremely low.