Choice of preamplifier: help

Based on your comments on the CJ preamp, I would strongly recommend looking into both/either the Calypso and/or the AR preamps (as also referenced by AudioFeil). Both of these preamps will deliver more detail and resolution than you will typically get with the CJ. They both will be a bit less "tube" sounding, but at the same time having an excellent balance of being musical without too much softness. In my system and many other systems that I have heard these preamps in, they impart just the right amount of "tubeness" without allowing the music to become "mushy". In my opinion (ie. my preference) the result is a very good balance. But for the record, I would take extra detail and resolution over extra warmth.

I would add the Aesthetix Calypso to your batch. It offers very good detail and resolution (better than most tubed preamps that I have heard/owned) yet is an excellent unit for tube rolling. It offers excellent spatial characteristics and is very musical without being mushy. I suggest doing a bit of a search in the forums as it has received lots of extremely positive feedback and is typically being compared against preamps in the $7,000 - $10,000 range, which is indicative of just how good it is. New it is within your price range, used you could save quite a bit. Others I would add to your list would be AR Ref. 3 or Ref 2 (used to get closer to your range). Any of these would be preamps that you can hold on to for many, many years. The Calypso will be a bit more detailed and resolving that the CJ. The CAT, I hear, is a very good preamp (based on comments by another member particularly that I have learned to have a lot of faith in and respect for).