Need help with choosing a tubed pre-amp.

After trying to find interconnects and what not to fix the sterile, somewhat harsh upper region sound of my SS system, I've decided to get a tubed pre-amp. I'm entering a new territory, and any road map or reccomendations would be greatly appreciated. My very modest system:

Adcom GFP 750 preamp (passive)
Bel Canto 2
Arcam cd72t
Audio Physic sub
Monitor Audio Silver 8i
Nordost Quattro Fil ic

I'm looking at a used BAT VK 5i and seem to like it. Does anyone have any experience with it and can relate the positive/negative to owning one. Or, if there are better alternatives within the price range.

I listen to mostly jazz and am looking for something smooth, warm, dynamic w/o overly warm or loss of detail and transparency. Or, the closest thing to a real life jazz concert. I know I've got a long way to go, but it's a start.

My thanks in advance.