Which DAC as a preamp?


Hi folks...I am looking for opinions regarding DACs to use as a digital pre-amp to drive my red dragon monoblocks. I am considering Audiolab MDAC plus, Musical Fidelity M6s DAC, NAD C-510, or the Audio Alchemy DDP-1.    Any thoughts as to which would be the best pick?
tfats
It’s going to be really hard to find someone who can directly compare them, right?  I have a PS Audio Stellar Gain Cell DAC/Pre and am happy with it.  I really wish it was easier to compare it to alternatives.
I have both the Audio Alchemy DDP-1 and the PS Audio Directstream DAC. Both are darn good. I think the PS Audio sounds significantly better (as it should given the price difference and the absence of features like analog inputs and a headphone amp).   The Audio Alchemy has an analogue preamp and a decent headphone amp built in.  The PS Audio DAC has just a volume control on it's output, but it is a very good volume control that did not degrade the sound in any way that I could detect.  I used the PS Audio direct to my power amps for several months and thought it quite wonderful. Still, when I swallowed hard and shelled out for the PS Audio BHK preamp, the improvement was undeniable and well worth it.  It sounds more life-like, real, organic, etc.  So my experience supports what ricred said above. That said, you can always get a preamp later, if you start with a DAC with volume control.
Classé cp 800,  or  ROTEL RC 1590 , both have analogue inputs too. I had the Rotel a few weeks, but brought it back to the shop, sound was not at all dynamic, 
The Lampizator Atlantic can be had with a volume control as can Aesthetix Pandora, those are both hyper musical imo 

ultimately i I have always found the preamp to improve things further.....

one of these days i will will get round to trying a Brinkmann Nyquist II direct....
i suspect it may have the grunt to drive 8m xlr

obly the listening shall tell....
Nuprime DAC-10.  Fully balanced preamp with a DAC included. Designed to work with their own "Class D" amps.  Has worked with W4S, Nord, Mivera, Nuprime and Job amps in my FR system.