The purpose of a preamp is to amplify low level signals to line level, i.e. the “standard” operating level of your recording gear. Microphone signals are usually way below the nominal operating level, so a lot of gain is required, usually around 30-60 dB, sometimes even more.

Do I need preamp for AMP?

Well the answer is no, you can't use a preamp without an amp. Even if the names of the two devices aren't obvious enough, it's necessary to understand that a preamp is basically a supplementary device that isn't needed in every speaker system.

Do I need a preamp with my audio interface?

n most cases today, any cheap audio interface will have built-in preamps already, but that doesn't mean you don't require an external pre-amplifier. ... To put it simply, if you want to get the most out of your microphone and achieve the best possible sound quality, using a good mic preamp is essential.