Take the left output from the DJ mixer or house mixer and connect it to the first channel of amplifier one. Connect the right output of the mixer to the first channel of amplifier two.
Set each amplifier to "bridge" mode. This is usually found as a switch on the back of the amplifier near the input connection. Bridge mode will send a mono signal to as many speakers as match the amplifier's impedance.
Connect amplifier one's outputs to a set of speakers. Connect amplifier two's outputs to a separate set of speakers.
Ensure that the added impedance of your speakers (4, 8, or 16 Ohms) does not exceed the maximum impedance for the amplifier.
Connect the left and right outputs of the mixer into the inputs of your crossover or equalizer.
Set your crossover or equalizer outputs so that the first two outputs are set to the mid- and high-range frequencies. The exact frequency crossover is up to the preference of the sound engineer, though it is generally in the 160Hz to 440Hz range for a DJ sound system.
Set a third output to the lower frequencies–generally anything below 440Hz to 640Hz.
Connect the first and second output of the crossover/EQ to the two inputs on the first amplifier. Connect the amplifier outputs to the left and right main mid-high speakers.
Connect the third output of the crossover/EQ to the first input on the second amplifier. Set this amplifier to bridge mode.
Connect the second amplifier to your subwoofers.