Connect all of the performance equipment you will be using to the mixer, ensuring that each of the turntables or CD players is routed to a unique channel on the mixer. The "line-in" jacks on the backside of the mixer are each dedicated to a specific channel. Each of the items you will be using to perform should be plugged into one of these jacks.
Raise or lower the volume level for each of your sound output sources using the vertical sliders located below the numbered "mute" buttons. These sliders will be used in place of the crossfader on typical DJ mixers. When you wish to slowly introduce a new song or segment of sound material, simply raise the volume slider assigned to the channel through which the music is playing.
Adjust the balance of high, mid and low-range frequencies with the blue and white knobs labeled "EQ," located above the numbered mute buttons. These knobs become especially useful when you wish to highlight a certain element of a particular song, such as a drum track or vocal line. Lowering the mid and low-range frequencies will emphasize a vocal line, while lowering the high-range frequencies will allow the drum and bass elements of the music to be heard more easily.
Turn the "pan" knobs to the left or right to adjust the location of the song in the stereo field. For example, if the knob is turned to the left, the song you are modifying will play primarily through the left speaker. This feature of the Mackie 1604 can be used to isolate certain elements of songs to the left or right speaker and allow the music being played to sound less cluttered.
Adjust the maximum volume output of a channel by turning the "gain" knob, located at the top of the mixer, to the left or right. If the knob is turned to the right, or clockwise, the overall volume level of the particular channel will be increased. This feature of the Mackie 1604 is especially useful if you are attempting to raise the volume of a song that is quiet --- relative to the other songs you are playing in your performance.
Plug your headphones into the headphone jack located above the master level fader. Press the "cue" button located next to the pan knob on each channel to send that channel's audio into the headphones. The audio will be routed directly into the headphones instead of playing out into the main speakers. This is a vital tool for the DJ and used frequently to synchronize one song's entrance with another's ending bars.
Interact with your audience by speaking to them during your DJ performance. The Mackie 1604 has 16 mic inputs, any of which can be used to plug in a microphone you can use during your show. The experts at Sweetwater, a leading audio technology vender, state that the microphone inputs have "impressively wide frequency range, especially in the low end, and even at extremely high gain settings." Don't hesitate to raise the volume on your microphone to speak over your music. The refined frequency range on the Mackie 1604 will eliminate the possibility of audio distortion.