Who is using their DAC as a preamp?

yes. I used it a couple years ago for about 2 or 3 weeks and was amazed how much better it sounded vs my Nova preamp. I'm getting ready to switch now and I will share my findings. I'm interested to see if I will "miss" my Rogue RP-5 preamp.

Another post about passive. Just try it, and, for a while. Believe me when I say, I had 2 preamps above an RP5 in sq, that colored the sound, held back details and information on my recordings, and unnaturally added balls and oomph to the music. Listen to SRVs " Tin Pan Alley ", a song many believe has been over played, but shows every attribute, and weakness, in a system. 

I boxed up most of my gear in preparation for an upcoming move. In the interim I’m using my Oppo 205 as a preamp. It sounds so good that I may keep using it as a preamp after my move.

I listened to my Project S2 this morning for about an hour or so. The soundstage was just as good as the Rogue. The Project seemed to present a more "pure" signal where the Rogue added a touch of warmth (it is a tube preamp). Bass, mids sound wonderful. High's extend just a little more (maybe because it is solid state). Nothing fatiguing. The tubes on the Rogue have probably 60-70% life left. 

I have been doing this for 10 years or more. I have not owned a pre-amp in a long time. I don’t miss it.