When broadcasting with the Blast Mic, if you are using the built-in microphones make sure to adjust your gain and do a Sound Check to monitor your levels.
Here's how you can use the gain on the Blast mic effectively:
Press the volume buttons on the left hand side of the device to control the microphone gain.
Note: The volume buttons control both the headphone monitor levels and the microphone gain. You can toggle between these two options by pressing the middle volume button.