Gain
Voltage gain describes the ratio of output signal voltage to input signal voltage, usually expressed in decibels.
Higher gain produces more output from the same input until a limit is reached. It does not by itself increase maximum output capability, and volume attenuation is a separate property.
Gain — Step-Up Transformer (SUT)
For a step-up transformer, gain describes the voltage increase for a stated tap and load. The transformer is passive: higher voltage is accompanied by a change in current and impedance relationships.
Keep published gain attached to its tap and loading. Nominal turns ratio and measured or stated loaded gain are not interchangeable, so a ratio calculation should not overwrite a published gain figure.
Gain — Power Amp
For a power amplifier, gain indicates how much the input voltage is increased at the speaker output. It affects the input level needed to approach the amplifier’s output limit.
Compare the stated input path and operating mode. Balanced-input gain, unbalanced-input gain, switchable settings and bridged-mode gain can differ; none should silently stand in for an unspecified overall figure.
Gain — MC Head Amp
For a phono head amp, gain raises a cartridge-level signal before the following phono stage. Fixed, stepped and continuously variable gain describe different available adjustments.
Keep each stated setting or range identifiable. A current-input design’s transimpedance in ohms is not voltage gain in decibels, and a zero-gain bypass position is different from active cartridge amplification.
Gain — Headphone Amp
For a headphone amplifier, gain determines how much the source voltage is increased before the headphones are driven. Lower gain can provide more useful volume-control travel with a strong source or sensitive headphones.
Compare the selected gain mode and input/output path. More gain does not automatically provide more maximum power, and an output-level or volume-control range is not the same specification.