[JFreak]

Chorus and every random process makes it impossible to perform a null test. I believe that the Waves plugins' "analog" setting is one such random process, which cannot null if you have two different bounces -- even if you don't change a thing.

That is why back in the analog days we took three different "bounces" because reverbs are random and sometimes some gear had not warmed up properly, thus changing the sound between "bounces".

Just live with it or don't use random processes. Null tests of real mixes IMO are worthless. The null tests are only useful if you really know what you're testing and why. In real world it's just as useful as comparing pink noise with levels 0.1 decibels higher and lower.