the tough question: Which preamplifier? and why

Well you have narrowed it down to all the wrong choices. I think, though I have never heard the Graaf that it is probably a really good amp, You might consider two preamps. One I am a dealer for deHavilland and the other I have a really good feeling for the Shindo, The deHavilland is just killer. So much music. I keep upgrading the system and the deHavilland Ultra Verve just keeps stepping up. Meaning that it might fit into an 80,000 system without a flinch. Check out their website at dehavillandhifi.com

When you consider system synergies and personal tastes, opinions may differ of whether to go active, passive or direct without a preamp. But recently I've become a believer, as many other have, that a good quality active preamp can do wonders to your sound system.

With my 2 channel system - (Wadia 861>>Leben CS600 Integrated Tube amp (32w/ch) >>Harbeth SHL5 speakers) - I was able to try different configurations using a integrated preamp, external preamp and no preamp at all. My Wadia 861 has a variable (digital) volume control and the Leben amp has the option of bypassing the preamp section to function as a power amp.

Running the Wadia direct into the Leben (used as a power amp) the transparency and clarity increased but at the expense of some harmonic leanness to the sound.

Using the Leben as a integrated amp (connecting the Wadia into the Leben's CD input) the sound filled out more and overall seemed better balanced and less fatiguing in comparison to the above.

But when I inserted an active preamp (Luxman C7f) to the power amp inputs of the Leben, there was a remarkable improvement to the sound. The most profound effect was how my Harbeth's came to life and open up with increased bass definition and extension. Music flowed more effortlessly with a natural ebb and flow that was slightly more upbeat than before. I did lose some transparency but not much, which was countered by richer harmonics and a greater sense of continuousness to the sound.

In my system the numbers match up well (sensitivity and impedances). The Leben amp itself is well endowed with large high quality transformers and components. However, perhaps it's more than specs that need to be considered. From my recent exercise I'd say active preamps (of good quality) do what their designed to do and that is amongst other things provide power drive to an amp and speakers. Try before you buy if you can.

Lightspeed Attenuator.

Incredible dynamics, explosive bass, articulate, transparent, meat-on-the-bones passive!

Everything I have experienced from active preamps (both tube and ss) with no grain, grit, glare, etc. and with typical passive transparency. So far, I have detected no discernible weaknesses, but evaluation continues. The only caveat is that the output and input impedances need to be compatible.

Here is a thread that may be helpful. Although it is a DIY forum, the author of the thread manufactures the Lightspeed for $500 US. In other words, if you aren't a diy person, it is available commercially.

I believe this thread is approaching 250,000 hits.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=80194&highlight=