Ahhh I think I see what you mean, so by shifting the pitch down, I'm also shifting the formants down. I once saw a trick by Qulinez I believe where, in order to b able to have his kick play different notes, he would pitch the bass of his kicks down but leave a second track with just the "knock" playing at the original pitch, and a fade to cut off the bass, so that everything was at the same volume.
Still, that method required each kick to be faded (easy to do as you just do the first one and copy/paste for the rest) but vocals could be trickier.
I'm looking at some vocal processing VSTs and Waves VX1 seems to be popular (and not a bad price). Would that achieve what I'm going for ya think?
Thanks again!