Just like the other subwoofers in the Thunder line, the Thunder-KMT218 is much more than a standard dual 18” powered subwoofer. This smart sub has an onboard Class D amplifier that delivers 2 x 2400 W at 4Ω with one of the two amplifying channels aimed at the sub while the other feeds a speakOn output connector to create many different speaker configurations, including single mid-high modules, multiple line arrays, or the passive version of an additional bass module.