Audio Interface

A microphone puts out a very quiet analogue signal. The interface amplifies it through a preamp, adds 48V phantom power if the microphone is a condenser and needs it, converts the result to digital, and hands it to the computer over USB.

Two things separate a good one from a cheap one: how much clean gain the preamp offers before it hisses, and how low the latency is when you monitor yourself through headphones. Dynamic microphones with low output, the SM7B being the usual example, need more gain than budget interfaces provide, which is why people add an inline booster. USB microphones have an interface built in already.