The sound level from my Mini Microphone 2+ is very low.
The speaker may not be wearing your Mini Microphone 2+ correctly.
Clip the Mini Microphone 2+ on the speaker's jacket or other clothing, or hang it around the speaker's neck using the lanyard. Be sure to place the device within 4-16 inches from the speaker's mouth.
The sound received by the microphone is very low.
Increase the volume by using the + button on the Mini Microphone 2+.
The audio streamed through the line-in connector or the FM input is too low.
Adjust the volume using the + and – buttons on the Mini Microphone 2+, or adjust the volume on the external audio device until you get the best sound level and quality.