BOSS Audio Systems BX45 Pre-Amp Electronic Car Crossover – 2-3 Way, Fine Tune Your High-Mid-Low Range Speaker Frequencies, Remote Subwoofer Control Included, Equalizer, DPS Audio Processor
Gold Sound Electronic Crossovers
Amazon.com: Sound Storm Laboratories SX310 Car Audio Electronic Crossover - 2/3 Way Pre-amp, with Remote Subwoofer Level Control, Use with Amplifier Stereo Equalizer, Line Output Converter : Electronics
Crossover basics and their functions
Dayton Audio 6-1/2" Down Firing Active Mini Subwoofer Kit with 2.1 Channel Amplifier 60 Watts
Amazon.com: Bass Rockers BRX3.1 3 Way Car Audio Stereo Electronic Crossover with Bass Enhancer 9V Out Put 6 Channel Bass Knob Included for Car RV Motor Home Bike Boat Harley UTV ATV
Amazon.com: Soundavo PSB-200 Subwoofer Amplifier with Crossover/Phase Control - 200W : Electronics
Amazon.com: Soundavo PSB-200 Subwoofer Amplifier with Crossover/Phase Control - 200W : Electronics
BOSS Audio Systems BX55 Pre-Amp Electronic Car Crossover – 2-3 Way, Fine Tune Your High-Mid-Low Range Speaker Frequencies, Remote Subwoofer Control Included, Equalizer, DPS Audio Processor
Monoprice SWA-200 Subwoofer Amp - Black - 200 watt with Crossover, Phase Control, Cool Class D Amps - Walmart.com
Amazon.com: Soundavo PSB-200 Subwoofer Amplifier with Crossover/Phase Control - 200W : Electronics