Which DAC as a preamp?

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. 

Haven't heard the ones you mentioned, but I had a Bel Canto DAC3VB in my system and in addition to being a great sounding DAC I found its preamp section to be indistinguishable from my Bryston BP6 preamp.  There are a couple 3.5VBs for sale here now, one almost unbelievably cheap.  Read the reviews, and yes the VB version is definitely the one to get.  Best of luck.