Adopt Texas Instruments TDA7498E chip, NE5532 op-amp. No pop, no audible noise, dead silent when nothing is playing through it; Built-in low pass filter, 220W X 1(4 ohms, 20 Hz - 120Hz, 0.04% THD, 18db/octacce) for subwoofer, Small simple compact design but practical and powerful; Advanced circuitry design, built-in speakers protection circuit, solid aluminum chassis for long time use; The new version of TP02 has one more sub freq adjustment knob than the old version, and the others remain unchanged. Quick tips: 1. Please plug the power cord into the amp THEN the wall, plug the audio cables into amp THEN switch on. Model    TP-02Output Power    220W for SubwooferTerminating Impedance    2Ω-8ΩInput Mode    RCAOutput Mode    Passive SubwooferFrequency Range    20Hz - 120Hz (±1 dB)THD    ≤ 0.04%SNR    ≥ 98dBInput Sensitivity    ≤ 280mVDevice Dimension    5.12 x 3.54 x 1.58 inchesDC Input Range    12-24VPower Supply    24V 4.5A