Who is using their DAC as a preamp?

I've been using the Oppo 205 as a preamp as well, straight to the mcintosh mc275, but am considering putting a ps audio stellar gain cell in between to see if there's an improvement.

For late night listening, I currently have a Schiit EQ (Loki) in the effects/tape loop connection of the Rogue. I just boost the lower frequencies a little...basically I use it as a loudness switch. Since the EQ has "true" bypass, I can just use it in line between dac and amp if I decide to ditch preamp.

An excellent choice for late night low volume listening, and the Schiit Loki at $149 is a bargain, does all what you said and more,   https://www.schiit.com/products/loki   just put it between any of these configurations: 
1: Between source and poweramp (if you have source volume control)
2: Between source and preamp
3: Between your preamp and poweramp.
4: Or in the tape loop on an integrated amp.

Cheers George 

There is a poster on another thread that uses a 1/3rd octave 31 band eq, as his passive device ( it has dual channel gain controls ). He compared it, flat, to 5 K preamps, and says it is superior to his ears. I have the same eq ( and I tried it via his recommendation ), but did not feel it came close to my Luminous unit in sq. However, it bettered some of my cheapie preamps ( RGR, Hitachi, AGI, Citation, GAS, SAE, Dynaco ). I sold my 2 megabuck preamps, which were both bettered by my Luminous unit.

I have been learning a lot about volume controls of late. In my years of having various components, I have never really thought about volume control quality. 

Back to the Mytek. Darko has a review up with a preference of an outboard preamp (BHK Pre-$6000). Darko does state, however,  the Mytek does sound very good job with direct input

Cleaner than the Sys...Ebay item # 253818627052...HiFi version. $40 or less, shipped. About what you would pay to build one. Promise..