On mixing boards this is an input to a channel that is specifically designed for line level signals. Unlike the XLR microphone input, which is designed for low level mic signals, line inputs are usually 1/4 inch connectors, and are quite often unbalanced, though this will vary depending on the mixer. Line level signals are usually much higher than typical mic level signal and do not need as much amplification to be dealt with by the rest of the mixer. As such, on some mixers, the line inputs actually bypass the microphone preamp stage providing for a pure signal path into the board. Regardless of this, however, line inputs are always capable of handling higher level signals and high impedance signals better than the XLR mic input.