Line vs. Mic Level

It's important to know the difference between audio level types to determine how best to handle your audio mix, the type of cable, and where to plug in your cables to an audio mixer. A line-level signal is approximately one volt, or about 1,000 times stronger than a mic-level signal. Because the mic audio level is significantly lower than line level, you will need some sort of pre-amplification or mic preamps to boost the signal so that it is audible. Audio mixers usually have mic preamps built-in, so you need to make sure that you plug your microphones into the appropriate port on your audio mixer. A line-level audio source can be MP3, DVD players, or simply the output from your audio mixer; however, some audio mixers can output line level or mic level audio.

It is crucial to match a device to the correct input, as there's no real technical tolerance for mistakes. Connecting a microphone to a line-level input will result in almost no sound at all because the mic-level signal is too weak to drive the line-level input. Conversely, connecting a line-level source to a mic-level input will cause the sound to be loud and distorted because the line-level signal is much stronger than what the mic input will accept.