What are you looking for in terms of sound, something very colored and syrupy or something that true to the source with speed, musicality and sheer dynamics?
My first recommendation will be Atma-Sphere MP-1 Pre-amp Fully Loaded with all dam options available. Put in the best tubes you can afford. I consider this pre-amp as one of the best around but you must learn to set it up properly with tubes. It is very sensitive pre-amp. I consider this as one of the best in the world. Its fully balanced, follows the AES48 Code, it can drive Long cables and you can set the system up well away from the speakers and amps. I have been using one for many years and no longer feel i need to ever change.
Other option is VAC, Its colored for sure, but sounds very good and i used to own it. I moved from VAC to Atma with no Regrets but still consider VAC very good pre-amps especially if bought second hand cheap.