This article explains how to broadcast on Mixlr using DJ software - 'Traktor', an external MIDI controller - 'Traktor S2', and Mixlr AudioLink. You'll be using Traktor to mix tracks from your PC, the S2 to control your levels, crossfader, etc and Mixlr AudioLink to pass the audio between them.
As the S2 has no available inputs, you will need to set up an Aggregate Device and use Mixlr AudioLink to route the audio between the S2 and Mixlr. These instructions would apply to any MIDI controller with no inputs.
Go to 'Audio Midi Setup' on your Mac, which can be found here.
Create a new device by clicking the '+' icon in the bottom left-hand corner, and select Create Aggregate Device.
Select to use Traktor Kontrol S2 and Mixlr AudioLink for your new aggregate device.
You can now rename your new aggregate device to make it easier to work with later.
You will find the audio preferences in Traktor's settings:
Ensure the Audio Setup settings in Traktor are as follows:
Ensure the Output Routing settings are as follows:
Ensure the Mix Recorder settings are as follows:
The audio recorder in 'Traktor' needs to show signals coming through, as pictured below. You will not need to press the record button.
Select your aggregate device as your audio input, and ensure the VU meter is registering the sound:
(Tip - If you're having problems with the Mixlr app receiving audio signal, check that you have the latest Traktor drivers installed. You can download the latest drivers here.)