What cable first

I currently have a B&K pre and B&K 200.2 amp with factory power cords. I also have an SVS powered sub with factory power cord. I'm considering upgrading in the power cords to something in the $100-$200 range per each peice, although one at a time. Which would make the biggest impact, if any? Also looking at ic's in the same range. I need to go from my Marantz cd player to my pre-amp. Maybe a power conditioner first would be better, and should my amp, sub and other components be on different outlets? If so, would I need multiple power conditioners? Any and all responses are appreciated, including witty sarcasm.