Installing An Equalizer
You can install an equalizer in a variety of spots: in your dash, under the dash, in the passenger compartment, or in the trunk or cargo area. Dash-mount units usually go above or below the receiver in the factory radio location. If there isn't enough room there, it can be mounted below the dash with a bracket or special kit. Some EQs can also be installed in a console or glove compartment. Trunk-mount equalizers install near your amplifiers, usually in the trunk or cargo area.
Wherever you decide to mount your equalizer, you'll need connections for 12-volt power, ground and a turn-on lead. In addition to the power connections, you'll need to feed signal from your receiver. Usually this will be a single set of patch cables. If your receiver doesn't have preamp outputs, you'll need an output level converter to adapt the receiver's speaker lines to a preamp connection. Many equalizers will include built-in line converters that will accept your speaker wires.
You will connect the equalizer to your amp with more patch cables. How many depends on your EQ and amps, but you'll need at least one set of connections per amp. If your equalizer's up front, be sure to run your patch cords down the same side of the car as any speaker lines. Don't run them on the same side as the power cable for your amp. That's a sure way to add noise to your system.