A microphone booster is a little preamp that's set up between your microphone and the microphone preamp of your audio interface or mixer. The booster amplifies the signal based on a fixed amount of gain, allowing you capture softer sounds like subtle vocals or plucked acoustic guitar strings using a less sensitive microphone. Microphone boosters are only used to help out and can't replace a proper microphone preamp. They run on phantom power - which means they don't require any additional power supply - and form an excellent layer of protection for ribbon microphones. The only downside of microphone boosters is that most of them are not compatible with condenser microphones.
