Probably because you're likely clipping the amp with too high of a gain or bass boost, which sends more power than 900 watts to the sub. At full clip it could be near double that. Also, moving to an Fi section since this is just a question, no hello. welll the FI Q i bout is fully upgraded.. dont know how to explain.. bought the upgrade so it could handle an additional 500 rms watts.. so the sub should be good for 1500 wrms so the sub should be good right even if i turn the bass knob that came with the amplier all the way up right?? Not if your clipping the signal, then no it won't be great. what do you mean by clipping the signal?? sorry im "Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum power capability. Driving an amplifier into clipping may cause it to put out power in excess of its published ratings"