do you use a pre-amp with your DAC?

I'd like to weigh in here because I've been doing some experimenting lately and I think what I've heard might be helpful. I have owned a Meitner BiDat that has it's own volume regulator and, for years, I have run it directly into various amps via balanced cables. The clarity and articulation are stunning. HOWEVER, I have read few articles about preamps that convinced me to try a tube based preamplifier now that I've upgraded my speakers (Thiel CS3.7's). I was a complete skeptic but buddy of mine in our local audio society brought over a VTL 5.5 tube preamp and we hooked it up. I was dumbfounded. The sound is more three dimensional, digital edge is reduced and the pacing is, for lack of a better term, more musical. I was dead set against this because now I have to buy a preamp and my budget is stretched. Now, I am sure that there a a whole host of preamps that might not improve your particular set up. I may have lucked out with the VTL. I plan on trying Musical Fidelity and Audio Research before I buy. Anyway, I thought you'd want to hear form a died-in-the-wool-who-needs-a-preamp skeptic like me.