One way to be truly in control is to admit that in fact you are never able to be fully in control. It stems from the concept that it takes control to admit such a thing and to still garner control after admitting it
It is interesting.... when we use vocaloids, even though they are their own singers and have their own charecter, we spend a lot of time defining in detail every single note, and you might say we have a lot of control (unlike a regular singer). We can make them sound like anything we want. But actually even though it seems we have all this control it's actually the opposite way around. We are being manipulated by the vocaloid in order to configure it in such a way that it sounds good. What I mean is, by sounding bad, a vocaloid can cause us to have to apply changes where we wouldnt normally. Because you see we simply cannot set up the vocaloid randomly, if we were truly in control we would spend hardly any time setting them up and we could do whatever we wanted. The fact that that there is essentially a fixed number of ways to make a vocaloid sound good means that we don't have as much choice as we might have thought.
So with Nana I feel like sometimes shes making me make changes. After I input some japanese I am forced to program her, when of course in a perfect world, it would work straight away, and I could write songs in 30 seconds. But this would be ridiculous, and no longer music.
No matter how we arrive at the conclusion. I beleive that all the vocaloids have in them already the power and ability to sound amazing, and we composers are just striving to release what is already there in some way spiritually.
For what is a relatively straight forward software, I am constantly being surprised by the sounds NANA makes, as I hope you will!