“a mixing console to your personality”
You may not be this bold or ferocious in your day-to-day life, but on stage you amplify these things in you that already exist.
|1⟩, |2⟩, |3⟩ are projections of the whole personality down to one “aspect”.
Then St Vincent’s idea is simply to lower and raise some of the
α, β, γ, δ … “sliders”. So like when doves cry inside a convex hull, it’s just linear combinations of pre-existing stuff, rather than the generation of “truly new” (orthogonal) things. (Properly in maths one needs multiple distinct examples to do linear combinations and create a span. I wonder if she would agree that “projecting” (isolating) the “elements” of her personality is a step requiring work in finding out what the aspects of the personality are, to amplify or mute them.)