Just did some experiments with this and it works good.
Situation: you have a very annoying noise/hiss coming out of the amp, and the noise gate was killing the tone or sustain too much for your taste?
What I did is record a track of the guitar NOT being played through the amp so just the hiss came out.
Invert the phase 180 degrees of this tracks, sum to mono bus with the regular take and you pretty much killed all noise.
Hope it helps someone
Situation: you have a very annoying noise/hiss coming out of the amp, and the noise gate was killing the tone or sustain too much for your taste?
What I did is record a track of the guitar NOT being played through the amp so just the hiss came out.
Invert the phase 180 degrees of this tracks, sum to mono bus with the regular take and you pretty much killed all noise.
Hope it helps someone