Line level is the standard signal strength used to connect devices to each other, while instrument level is the smaller signal typical of guitar and bass pickup outputs.
The basic idea
Connecting to the wrong kind of input causes sound that is too quiet, distortion, or added noise.
What to check when using it
Set the LINE/INST switch on your audio interface to match the device you are connecting.
Mic level is a smaller signal still, and it differs in requiring a microphone preamp.
