Basically this is the same thing as sensitivity – putting the word “input” in front of it is somewhat redundant. Input Sensitivity controls are commonly found on amplifiers and other audio equipment. While they appear to function like any volume control, there is a distinction between the two. They are nearly the same functionally in that input sensitivity controls will change the volume or output of an amplifier. The way they work is by padding down the input signal to varying degrees as it enters the equipment. They will not boost the signal – turning an input sensitivity control all the way up generally results in unity gain. They do not control the gain of the device either (as some volume or level controls do); they merely adjust the (input) sensitivity so it can be matched better to the output of the device before. The distinction between this and gain or volume is subtle, but important to understand because generally adjusting an input sensitivity control will not have much of a detrimental effect on a device’s signal-to-noise ratio, whereas a standard volume or gain adjustment can. There can also be differences in how they affect things like headroom and dynamic range. However, the degree to which these statements are true in practice really depends on the actual implementation of a given unit.