Are you running this? Would appreciate your comments. Does the RME ADI-2 work well as a pre-amp from a functional standpoint? I'm aware of Amirm's measurements of it as a superb DAC.
I am running the RME ADI-2 DAC as a preamp, with a refurbished 2x140 watt rms Quad 606-2 power amp. Sonically both are more than good enough of course although one day I might just treat myself to a more powerful class D power amp (I bought the 606-2 as a sure match to my Quad 2805 electrostatic speakers, and because at 350 euro refurbished and all it was dirt cheap).
The RME DAC is just about the most functional DAC/preamp on the market because it has all the benefits of traditional preamplifiers, such as tone and balance control, and remote control, plus extras such as some parametric filters, dynamic loudness, and an auto reference level system that combines the best of digital and analogue volume control. What it does not have is analogue inputs, but I don't care, and if you do there are solutions for that. Since the number of inputs was insufficient for my digital sources, I use an automatic input switcher:
https://www.tindie.com/products/Beni_Skate/automatic-spdif-opticalrca-audio-switch/ RME tested this and was impressed.
Build quality of the RME is excellent, and so is support.