best tube preamp under a 1000 for B&K 200 sonatas?


I have a pair of the B&K mono block sonatas...currently using a B&k ss pre....I would like to step into a tube pre but don't want to spend more than a grand. Definitely buying used. Running paradigms studio 60's. All suggestions welcome. Thanks
magnus89
Its a hard price point even for something used. If you can find an old Sonic Frontiers SFL-1, that would be my first choice. Its one of the few low cost preamps that actually sound very good. Quicksilver is another good choice.
Can you explain a quickly about the output impedance of the preamp? What should I stay away from? I have seen a few Carys on here in my price range.,also what about eastern electric min max?