A preamplifier, often called a preamp, prepares an audio signal for amplification and subsequent transmission to speakers. In essence, the preamp handles all necessary processes before the audio signal, originating from a music source, is amplified and sent to the system's speakers.

Audio systems, whether traditional hi-fi setups or modern self-contained units like the Sonos Era 100, require amplification to power the speakers or drivers that produce sound. Passive loudspeakers, common in hi-fi systems, do not generate their own power and rely on an external amplifier to function.

The role of a preamp is to optimize the audio signal before it reaches the amplifier. This may involve boosting the signal, impedance matching, and applying equalization to improve the sound quality. In simpler terms, the preamp ensures that the amplifier receives a clean, strong signal that can be effectively amplified and reproduced by the speakers.

Whether an individual needs a preamp depends on the specific audio setup and the sources being used. For example, turntables require a phono preamp to boost the weak signal from the cartridge to a level suitable for amplification. Similarly, some microphones may require a preamp to increase their output signal. However, many modern audio sources, such as smartphones and computers, already have a built-in preamp, making an external preamp unnecessary.

The integration of preamplification into self-contained audio systems reflects a trend towards simplification and convenience. In these systems, the preamplification and amplification stages are combined into a single unit, eliminating the need for separate components. This approach is particularly appealing to consumers who prioritize ease of use and space-saving design.