Audio
Mic Level vs Line Level
01 — Definition
Four levels not to be mixed up. Mic level (−60 to −40 dBu) calls for plenty of gain: preamps commonly offer 60 to 80 dB of it. Pro line level runs at +4 dBu nominal, consumer at −10 dBV nominal, and instrument level sits between mic and line, at high impedance. Send line level into a mic input without a pad and the preamp clips; the reverse — mic into a line input — is very nearly inaudible.
02 — In the field
A DI box does it all at once: it converts high-impedance instrument level into low-impedance mic level, and unbalanced into balanced. Essential on stage.