DY: The Shevet HaLeivi’s Shittah is that anything made to sound good inherently counts as not a capella.
That’s not what I’m referring to; I’m referring to something I heard from R’ Belsky, that when vocals are digitally manipulated so that they no longer sound like something which can be produced by a person, they are no longer considered vocals, it’s considered instrumental.
I think I saw it on the ‘net at one point as well.