QuasiUnaFantasia
CeDur Someone "sampled" Pianoteq.
Pianoteq does not have a Bösendorfer, nor an Estonia.
EDIT:
I have not fallen completely for Sofia's piano's, because I hear a distortion which, once heard, I cannot unhear. My guess is that this has come about through a very heavy-duty noise-removal procedure which removed more than just noise. It is certainly possible to remove high-pitched noise through algorithmic means, so having a very low noise-floor is not indicative of the sound being artificial in its origin.