What are the more subtle sounding tube preamps?

CJ Classic is definitely on the warmer and darker end of the spectrum. If you want rich and organic but not dark try Audio Note.

+1 for the Odyssey Candela, more preamp for less money may not exist. Tube rolling will set it up for just the sound that works for you.  You'll have to spend 5x the price to beat it.  Pair it with an SS amp and you get tube smooth with great control and definition.   I'm loving it with cryo'd Mullards and a Khartago Extreme. 
what a deal!
Support from Odyssey is first class... 

I have to disagree that the Classic 2 is dark.....its well balanced and very lifelike and dynamic in my system....  its anything but dark. 

The only downside is that it has no remote, in terms of sound quality it is a sleeper and should be auditioned.  Im willing to bet that most people talking about it on forums have never heard it and are slamming it becausd it lacks features that you come to expect.   

I listened to my pre in what looked to me like a $50k system and that was all i needed......it sounded great in a system where the associated components were many times its price.

I should have noted my unit is a 2SE

The Rogue Audio will give you the great dynamic range combined with tube smoothness that's not overly tubey.  I had the Hera II for a number of years and it was the best I had (unfortunately had to downgrade due to space limitations).    The new Rp-7 is balanced and rp-5 unbalanced and are both excellent compared to anything listed on this thread.  Pairing with the m-180s or the Hydra/Medusa hybrids is amazing.  The best bang for your buck unless you want to spend 3x to 4x money.  Also hand made in USA.  My 2 cents...