to expand on what Teacher is saying if I may:
my GR
ME1NV is my best pre, I wont say its a "Night and Day Difference" over my other pre's (people love to use that term to justify their purchases) I see things a bit different.
individualy, a piece of quality gear yeilds smaller improvments in the overall scheme of things, its only when you complete the entire chain by adding a great pre, a great mic, a great set of converters, etc.. does the end result sound like a "Night And Day Difference" over Jr's recordings.
One thing you will notice when layering all your tracks with a nice pre however, is your overall mix will improve compared to that mid range haze/mush sound your dbx collects over an entire mix. its difficult sometimes to sing, drum, play into two pre's, compare them and hear a "huge" difference. sometimes we want to hear those differences so bad!
my pre's:
ME-1NV................main use
RNP......................frequent use
DMP3....................some use and drums
ART Pro MPA.........seldom used only drums
DBX 376...............seldom used only drums
Mackie 1202VLZ...seldom used only drums