i had an rme adi2 about two years ago, the fs2 unit with akm chip
i felt it was a feature rich, well built, very clear and precise sounding dac, best run without internal volume attenuation (as this was done in the digital domain and could reduce resolution if high attenuation levels are used) - a great value in terms of sound and control over the sound, for the money...
at the time i also had the ayre codex, mhdt stockholm and chord qutest in house for comparison, and i felt the rme was excellent in its quite precise, very clear presentation of the music with extended frequency response -- but its weaknesses were a more mechanical, less organic presentation than either the ayre or mhdt (a nos tube buffered dac), and had a notable stronger central image without the appreciable soundstaging width or depth of the other dacs (the chord was the best in this regard, had tremendous spatial imagery, followed closely by the mhdt then the ayre) -- as such i concluded the rme is best suited for headphone listeners where imaging ability is less valued than the other positive attributes the rme brings its user