Volume control vs. attenuation control

Ergo, my integrated amp has a "gain" setting which defaults at zero gain and which can be adjusted to plus or minus settings. So the zero "gain" setting is set at an arbitrary position by the manufacturer, and actual amplifier gain would be the highest "gain" setting. And "gain" is a misnomer (sp). Technically, the "gain" setting is an attenuator, a voltage divider. Right?

Not exactly. Gain is simply the ratio of output to input. the 0db setting isn't arbitrary, it is the point where out = in.

If the gain is less than 1 (output less than input) we say the preamp is attenuating the signal. With 2 volts in and one volt out the gain would be .5

If the gain is greater than 1 (output more than input) then it is amplifying the signal. With 2 volts in and 4 volts out the gain would be 2

If the output equal the input the gain is 1.

This is commonly expressed in dB which for voltage is 20 times the log of the gain. If gain is less than 1 that comes out as -dB, a gain of .5 is -6dB. A gain greater than one comes out +dB. a gain of 2 is +6dB. Unity gain when out = in comes out to 0dB so that isn't an arbitrary position.

Your preamp is attenuating the signal when you have it set to -dB, amplifying when it is set to +dB, and not changing the level when set to 0dB.

It accomplishes this with a combination of an active stage that amplifies and a voltage divider volume control which attenuates. The volume control can have a gain from between 0 and 1 and the active stage some positive amount. Multiply the 2 together to get the overall gain.

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Thanks for the iluminating explanation.