Which DAC as a preamp?

The DDP-1 is an excellent DAC with a good preamp in it. Very detailed with texture. I have a couple very good tube preamps so don't use it for that purpose. FWIW, TAS did a review on it a while back & stated that the preamp portion compared to a $2000 unit.  

Listening to the Mytek Brooklyn (original) driving a pair of ICEpower monoblocks. Could not be happier. :)

Every system and everyone's hearing is different.  I've owned the PS Audio Directstream, Bricasti M1, Jeff Rowland Aeris, and now the Chord Dave. I didn't prefer any of them direct. To my ears everything sounds better with a preamp inserted in the chain. 

I use a McIntosh D150 as a DAC for my MCT450 transport but it is designed to be used as a preamp in a digital setting.  I a very happy with it as a DAC.

tfats

Your going in the right direction for the most transparent/dynamic sound, by looking for a dac that has volume control in it.

But there are two ways this volume control can be done in a dac.
1: In the "digital domain" which to is best "if" the volume is not reduced too far, so to introduce "bit stripping" (a reduction is resolution), this can happen if the volume is reduced below approx 75%

2: A dac with an analogue domain volume control, no "bit stripping" problems with these. There can be impedance matching problems to an amp if the amp is lower than 33kohm input impedance.
The earlier Red Dragon’s had a low 12kohm input, they saw this error for some pre’s and the later MkII Red Dragon it’s said to be much higher (they don’t say how high) to accommodate these pre’s

Red Dragon: " Red Dragon Audio designed the M500MkII with customer feedback at the forefront of the process. Increased Input Impedance allows our amps to be paired with all preamplifiers - even the most esoteric tube preamps."

Cheers George