What is the best preamp for Carver monoblock tube amps?


I have a great preamp in BAT Rex2 tube preamp. I am considering getting a Carver tube amp such as used Cherry 180 or the newer 350. Rex2 is an excellent preamp, but I don't know how well it will match with a Carver. I am using Soundlabs e-static speakers. What preamp do you recommend? 
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Get the order placed for the Carver amps, may take a few weeks if not in stock on the shelf.

 Get the preamp a tune up is all.
amazing preamp!
get an Octave 10 Audio pre amp.  That's what I have connect to my 350s.  Hand wired, great tubes and made in the US.  I love mine, if you want to spend 3xs the money for a name (that's not the quality and handcrafted). your friends will know that's up to you.  My S# is 13 on the 10 btw.
bestMark
atma......
Under 1-ohm capability  Input Impedance:
100 K ohms (RCA)
Source Impedance:
1.7 ohms not sure the spec you are looking for for the Carver 350s  I assume 100K but....
BestMark