I’m looking for suggestions for a tube Pre Amp

My Current System:

Benchmark USB DAC1
NAD M3 Integrated Amp
Vandersteen 2CE

For a long time I was rocking a Wavelength Brick USB Dac (which is a tube dac) as my source component, but have now moved to a Benchmark DAC1 USB. I like the idea of having a tube somewhere in my system but I don’t really think I can afford to maintain a tube amplifier. That being said, I’m considering adding in a nice tube preamp then use my NAD as a power amp only (and potentially moving away from the integrated NAD at some point).

Can anyone suggest a moderately priced Tube Preamp that would complement this system well?
Can you be more specific than "moderately priced"?
Sure, somewhere between $1-2k
For a smidgen more than 2K, you can get a used Modwright LS-100 for around $2200.

I believe you would be very happy with it.
Define 'nice tube preamp'. Are you looking for an old-fashoined warm, lush, tubey sounding tube preamp, or a more modern, articulate, transparent tube sounding preamp?
Jmcgrogan2 - Excellent question. I think I'm looking more for the warm, lush and tubey kind of sound. That's what I feel like I had when I was using the Wavelength Brick tube DAC as my source.
New or used?
Preferably used... I hate paying retail. But I would be willing to do new if there was a in-home trial offer of some kind.
Have you tried to use the DAC1 as preamp to drive the NAD? Adding an unnecessary component in the middle, be it tube or otherwise, may not be a good idea.
I've been looking at YS Audio tube preamps, as they have a true balanced design, with balanced input and output. That would work great with your new DAC. Worth a look, especially at the SE edition.

+1 on the Modwright LS-100.
I would look at an older BAT or Sonic Frontiers. A VTL 2.5 is excellent as well.
Sidssp - IRT the preamp in the Benchmark. I use the DAC in Calibrated mode which appears to bypass the pre in the DAC. My guess is that the pre in the NAD M3 is superior to the one in the Benchmark.
If you are looking for the warmer sounding tube preamp, look for a used Conrad Johnson, Cary or BAT. Happy Hunting!
I think you have a nicely balanced (non-tube) system as is.

If changing, I would keep DAC-1 and use as a preamp. Get a tube power amp and some sensitive speakers (ie. Tekton, Klipsch, etc.) That way you get tube sound in a smaller amp that is cheaper to re-tube. If you like what you hear but need a pre for switching among more sources, get a passive.
The Jolida Fusion 3000 preamp retails for $1299. You might consider a tube integrated amp. A Rogue Cronus is in the ballpark of your preamp budget, as are many of the Jolida products. Topping out your budget, for instance, would be a Jolida JD801BRC (70WPC). Also, with an integrated, you will avoid having to spend part of your budget on interconnects.
VAS (Cayin Distributor) Citation I. This is a knock off of the HK unit of yesterday. The design then and now is outstanding.
There is a Manley Shrimp listed right now for just over $1100. That's a very nice preamp and no it's not mine. I have the Jumbo Shrimp.
@Slappyjam: The preamp in the DAC-1 is very good. I actually like it better than going through my BAT VK-51SE. Why don't you give it a try. It doesn't cost you anything.
01-06-13: Wilsynet
For a smidgen more than 2K, you can get a used Modwright LS-100 for around $2200.

I believe you would be very happy with it.
+ 2. The LS-100 is a very well engineered preamp. It is warm and lush sounding & Dan Wright is a great guy to deal with to boot. Best of all, if you get the upgrade bug in future you have an easy upgrade path to upgrade to 'SE' status.
Pre owned Audible Illusion M3 or M3A
Used ARC power amp 100.2 ss
will bring the performance.
I am very happy with my Modwright SWL 9.0...I had Dan upgrade the power supply with the tube rectified section and other caps etc...This has made a great difference and with my new Oppo BDP105 for my source, my system sings with harmony no matter what I throw at it...
Given the components you have I agree with Jmcgrogan2. Particularly the CJ preamplifier. A CJ, and a good SS power amp like a Brystom 3bst sound fantastic with the Vandy speakers. This would take you system to a new level, thought the Nad amp is no slouch either. The recommendations about the the others like the Audible and Modright will not provide the same level of warmth you seek and the match for what you have.
+3 on the Modwrigh LS100
Look for a used VAC Standard LE for $2k to $2.5k. It is designed to play well with most systems and the sound is glorious. Best kept secret in preamp cost/performance.

Enjoy your search!