The signal from a microphone can vary from as little as a few millivolts up to 1V (RMS), depending on what is being recorded and the microphone being used. However, passive splitting cannot be used where multiple destinations are required, because the signal would be greatly attenuated. There is inevitably some signal loss, but that's often preferable over an active solution because the noise penalty is generally much lower. If microphone levels are being split, it's common to use nothing more than a purpose designed transformer. There are many other applications as well, and there isn't a single solution to all possible requirements. Signal splitters are common in recording and news gathering environments, especially where a live broadcast or recording is made of a live performance.

Microphone signals also commonly need to be sent to multiple destinations. It can be a direct feed (from the instrument's output) or from a dedicated 'line output' as provided on some instrument amplifiers. Commonly, a signal is taken from an instrument, and sent to a stage amplifier and a mixing console. This article may appear to be part project, and the schematics shown will all work, but the primary purpose is to discuss the various options when an audio signal has to be split to feed the signal to two or more different pieces of gear.

Audio and mic splitter