The average audio voltage level of a signal at a particular point in an audio system above 25mV RMS. The output level of a preamplifier is typically line-level, and the input level of a power amplifier is line-level. In home or semi-pro equipment, the input or output operating level is usually -10dBV. In commercial audio systems, line-level is metered with a VU meter, where 0VU corresponds to 0.775V RMS of a signal. The line-level in professional audio systems may be +4dBm (1.23V RMS) or (archaic) +8dBm (1.95V RMS) or even +20dBm (~9V). Typical line-level audio signals include synthesizer outputs, mixer outputs, and effects outputs. As opposed to mic-level.