Similar to eclein, I use a One.2 with the Grant Fidelity TubeDac-11 with a vintage Sylvania tube as both the DAC and Pre, and find it to be an excellent combination. Now my old Grant Fidelity B-283 is on the sidelines waiting a new home.
I have used some ADS L710's with this setup also although usually it powers NEAR 10M monitors for nearfield listening at my desk.
Incidentally, the TubeDac-11 has a non-tube out also which is great for hooking up a tube headphone amp if that's your thing.