I don't know the answer to your question but it makes me wonder if this volume control is a user controllable version of Apple's Sound Check?
I sometimes use the equalizer in iTunes, which has a dB slider which sounds similar to what you are describing, to lower the dB setting on ripped CDs that were recorded at high loudness levels. (Not even sure that makes sense but they sound better to me that way.)
I sometimes use the equalizer in iTunes, which has a dB slider which sounds similar to what you are describing, to lower the dB setting on ripped CDs that were recorded at high loudness levels. (Not even sure that makes sense but they sound better to me that way.)