Powered sub for massive low frequency support.
For those who prefer the simplicity of a self-powered subwoofer, there's the JBL JRX118SP 18" Compact Powered Subwoofer Cabinet. JBL started with the same woofer used in the non-powered JRX118S and added a specially designed amplifier with 500W (peak) and 300W (continuous) power output. The stereo crossover network is great for systems with EON or other powered satellite speakers. Peak limiter that protects the amplifier and speaker from clipping.