Simple Explanation

The standard signal level used to connect most audio components before amplification.

Concise Technical Definition

An analog audio signal with a voltage typically ranging from –10 dBu (consumer) to +4 dBu (professional), used to interconnect preamps, source devices, and powered speakers or amplifiers.

Layman-Friendly Analogy

Like the pressure in a garden hose before it hits the nozzle—enough to move water, but not full blast like a firehose (speaker level).

Industry Usage Summary

Line level signals are used between source devices (CD players, streamers, DACs), preamps, and amplifiers. They’re sent via shielded cables (usually RCA or XLR) and must be amplified to speaker level before driving loudspeakers.

Engineering Shortcut

Preamp/source signal voltage (–10 dBu to +30 dBu); not speaker power.

Full Technical Explanation

Line level refers to the voltage level of an analog audio signal that is stronger than microphone level but not yet amplified to speaker-driving power. It is the most common signal level used to interconnect components like CD players, streamers, DACs, preamps, processors, and powered subwoofers. Consumer audio gear typically operates at –10 dBu (roughly 0.316 volts RMS), while professional audio equipment uses +4 dBu (about 1.23 volts RMS). Some line level outputs, especially from studio gear, can reach +30 dBu. Line level signals are transmitted via RCA, XLR, or TRS cables and require shielding to prevent noise. These signals are fed into power amplifiers, which then increase them to speaker level for playback.