Behringer SUPER-X PRO CX3400 Component Rack SUPER-X PRO CX3400 High-Precision Stereo 2-Way/3-Way/Mono 4-Way Crossover with Limiters, Adjustable Time Delays and CD Horn Correction  Professional stereo 2-way/3-way/mono 4-way crossover featuring state-of-the-art Linkwitz-Riley filters with 24 dB/octave Individual Limiters on each output for optimal loudspeaker protection Adjustable time delay for phase alignment between drivers CD horn equalization for constant directivity horn compensation Absolutely flat summed amplitude response, zero phase difference “Low Sum” function provides mono output for subwoofer operation