Re: Trivia: Why is it called Gain?
The gain of an amplifier it the amount it increases or decreases the amplitude of the input signal.
To work out an amplifier's gain, you divide the output power or voltage by the input power or voltage. To work out his in dB, you need to use a logarithmic equation.
For the voltage gain this is 20log (Vout/Vin)
For the power gain this is 10log (Pout/Pin)
So, your gain controls are labelled gain, because that is exaclty what they control, the change in voltage or power that the amplifier produces, which is refered to as the gain of an amplifier circuit.