Tube Preamp for an audio zone gaincard-like AMP1

I currently have an Audiozone AMP-1 amp directly connected to my cd player. It is very transparent and forward, although maybe a tad too bright for my tastes. I am looking to make the sound a bit smoother and I figured that adding a tube preamp would acomplish just that. I am looking for a tube preamp that is under $1500 (though under 1k would be even better) that will be able to smoothen the sound while not degrading the detail and expansive soundstage that my AMP-1 produces. I have no experience with tube preamps, but have compiled a short list (ok maybe it isn't that short) of those that fit the bill:
Decware SE84CSP
Welborne labs ultrapass bp
Rogue audio preamp (the new titan series)
eastern electric mini max
blue circle bc21
deHavilland
T.A.D. 150
EAR Yoshino

Let me know if you think any of these stand above the rest or represent the best value. Feel free to suggest any other tube pres not mentioned. thanks