Tube Preamp - What to buy?

Looking to take my first venture into the tube world and going with a tube preamp.  My budget is up to $2500 and willing to buy used or new however realize with my budget that used is probably a better path. I would like to have a built-in MM phone stage.  I am use to having a remote and tone controls, so that would be nice however not a necessity.  

For further information my speakers are Revel Performa3 F206 and the current amp(s) is Conrad Johnson SA-250 and I also have a Rotel RB1552.  I many be looking for an amp upgrade in the future, but one thing at a time. 

So far I have been looking at used Audio Research and Conrad Johnson preamps but very open to opinions on brand and model.  Thanks and I look forward to your opinions and experiences.