Tube Preamp Advice Needed

I do not have the opportunity to listen to any of these but, after reading posts in this forum and reviews on Audioreview I have narrowed my choices to these tube preamps and I need your opinions on which one would work best in my system. I am looking for a slightly warm to very warm sound due to my bare wall great room which is 32 x 24 with a vaulted 21 foot ceiling. My system is:

Classe 25 balanced two channel amp (250 watts) for midrange and tweeters
NHT SA-3 amp for woofers
Wadia 20 CD transport
Wadia 25 DAC
NHT 3.3s
Cardas Golden Cross XLR Interconnect (DAC to Classe amp)
Cardas Golden Cross bi-wire speaker cable
Aragon Soundstage on order which I will run through the surround processor loop of the tube preamp

If I can get the same quality of sound from my Wadia 20 hooked to the Aragon I will sell the Wadia 25. I am concerned that I may not because I am using the glass fiber optic connection from the Wadia 20 to Wadia 25 and I don't know about the difference in the DACs. The Wadia 25 is then connected via balanced interconnects to the Classe 25. The Aragon only has a Toslink fiber optic connection to hook the Wadia 20 to. The Wadia 20 does have a single balanced output which I might be able to connect directly to the new tube preamp. Too many variables for me.

My tube preamp choices are:

BAT VK50SE
Joule Electra LA-400
Conrad Johnson 17LS
Audio Research LS25MkIII

Thanks for your help and advice.