Some general info to help(relating to working in Pro Tools). Traditionally, GAIN refers to the input level of your preamp. Then there is "GAIN STAGING" which relates to how you set levels thru several devices(or plugins) in an audio chain(think Preamp>EQ>compressor>amp). Then(where it gets a bit confusing) there is the AudioSuite GAIN plugin. This might have been named better as it changes the LEVEL of the audio file(by a db amount). This is very similar to using the AudioSuite Normalize) plugin(which changes the LEVEL by a percentage amount where 100% is using the full 0dbfs volume(not so intuitive).