An output dictates where you want to send the signal once it has been processed by the mixer. A DJ mixer usually has two sets of outputs, one that ends up at the audience called a master output and a Booth Output. These signals are the same, but they will generally have separate volume controls.
This is the output used to connect the speaker you will be using to mix with in the DJ booth, known as the booth monitor or fold back speaker. Connecting the booth is the same as the master and record so that the DJ can hear the music before the Audience. This helps because if the speakers are far away, the DJ may have troubles, hearing delayed music playing through the master speakers
A booth is where the DJ is Located and is referred to as the DJ Booth. These outputs to the extra speakers are important because they act as a reference for the DJ. The reason that the master output is not good for this purpose is that when the speakers are a large distance away from the DJ and facing in the audience's direction, a latency will be introduced and this can become a problem because you will be hearing the music slightly late and if u mix using the master speakers, the songs will be out of time when you send the new track to the main speakers. Not all mixers have booth outputs in the form of an RCA (red and white) cable to connect to a speaker. In that case you will be heavily relying on your headphones to mix. Some mixers will allow you to play one song in each ear, and because there is no latency in your headphones, you can accurately cue your next song, knowing that it will sound as it is in your headphones.
The Master channel is where all of your inputs are combined (summed or bussed is another term used to describe this process) together to be sent out as a Stereo Channel at the master output and Booth Output. A stereo channel means that there is 2 individual tracks of music. One is the right channel, coming out of the right speaker and one is the left channel, coming from the left speaker. The other option is to have a mono source that will play only one track of music intended for use with only 1 speaker. An alternative option is that you can summ your stereo tracks to mono, resulting in the two individual tracks of the stereo source to be combined and sent equally to all the speakers.
Stereo summing can be useful because you can control the volume of the speakers individually, say for instance one of the speakers has been placed behind you and is blowing off your head. Another stereo technique involves some of the musical effects that might be available on your mixer. A simple example would be a panning effect, meaning that the music can pan from side to side at a certain rate to give the impression that the sound is moving.
Mono summing also has its advantages as the music will be distributed evenly throughout all of the speakers. The main advantage is that you will actually get a slight volume increase of about 3 decibels because your are adding the two stereo tracks on top of each other and sending them through all speakers. Many clubs use this to their advantage and in most clubs the music from the mixer is summed to mono by the amp before it goes to the speakers.
Record Output – Is there for exactly what it states: to connect whatever it may be that you are using to record, such as a PC. It is there to ensure you get the best possible quality when recording. To connect the record output you simply connect the RCA leads into their corresponding outputs the mixer.