Ralphiano
This is a good description. When approaching a distant piano (or perhaps, one being played in a far room of the house, around a corner or two), the most apparent deficiency would be the absence of volume. However, a secondary deficiency is that through the effects of intervening walls, hallway turns and corners, and other factors, there is also a difference in the sound quality apart from volume. If one could amplify this sound it would just become a louder distant sound. It seems as if there is some element in a real piano tone that Pianoteq misses.
I've been tinkering with Pianoteq recently. I've been greatly elevating the velocities of my VPC1 keys using the VPC1 Editor while simultaneously diminishing the volume level via the Ptq Note Editor, and vice versa. I think I'm starting to notice that the distant characteristic is part of the note fundamental sound, not the harmonics, attack, or resonances. When sounding Ptq notes with hammer hardness reduced and hammer noise reduced and with velocities set low to remove the brightness, the Ptq note should sound like a plucked or strummed piano string. But, it does not. The stripped down Ptq notes just sound like an on-tone sound from some distance away.