Microphone preamps are used to amplify the signal from a microphone so the signal can be outputted at "line level", enabling routing onto other audio circuits / devices including mixing desks, rack processes etc. Many microphone preamps are in built into audio devices (such as mixing desks and audio interfaces), though high-end studio preamps are commonly sold as separate units. A mic preamp will normally have a gain control which allows the user to adjust the sensitivity of the microphone.

Singers and vocalists should spend time learning to work with the gain of the preamp to adjust the sensitivity to suit their singing style and microphone handling habits. If recording in a studio with a range of different microphones, consider a preamp that has a adjustable impedance control, as microphones respond differently to different impedances.