So, if I am working in Nuendo for example I might have let’s say a human voice on an audio track. I will
set the initial level using event volume in the project/edit page. I do this directly on the event itself. So this now is the first point of possible gain change.
Then on that channel I might have an EQ and then a compressor, on pre-fader inserts. So both of those will get the level after step 1 above.
Then I will use the fader to ride that human voice the way I want it. If I lower the level now it won’t do anything to anything that happened before - it won’t change anything in step 1 or 2. That’s because in step 1 the change was done before the audio track/channel, and in step 2 it was done _pre-_fader.
I might then use a brickwall limiter in a _post-_fader insert. This is just a ‘safety’ to avoid any signal going above a specific value. If I hit this limiter hard it will sound bad. But as long as steps 1, 2 and 3 above were done well it actually rarely limits the signal at all. But, if I end up increasing the level using the fader in step 3 above then it will change the amount of limiting in this plugin, because the plugin is after the fader.
So as long as you place your plugins in inserts that are _pre-_fader you can adjust your fader without changing what happens in those inserts.
PS: This of course excludes what happens when you send the output of your track to a group or output and then have inserts on that group or output. If you do that then again you have to consider what the fader does - because those inserts would be after the fader on this channel.