I bought a AES AE-3 tube pre-amp for the very same reason. It made a huge impact in my system and brand new is in your price range. I really think it has been my best purchase to date. Tube rolling is very easy since it only has two tubes and you can buy it with or without remote.
Tube Pre-amp beneficial?
Will a tube pre-amp "warm-up" my Martin Logan SL-3s if I am running a SS amp (Sunfire)? Or, do I need tubes throughout? I am currently using an Adcom GFP-565 in bypass mode, and I would like to upgrade the pre (staying under $1000) and add a remote, any recommendations from people with similar equipment would be appreciated.