Sorry for the massively open question, finding it hard to describe what I'm after..
Due to the nature of older analogue pass filters curves I am aware they can create a bump before the cut of frequency which can be implemented as a kind of focus, I've done it software before, and I find myself doing a lot of shelf lift, filter cut just after on tracks where the energy is sitting wrong for example.
Is anyone using analogue filters to cut and focus on a 2 track mix? I know there are a few German ones floating around..