I can't hear that the piano is out of tune. The sounds seems a bit "tinny" and is not mellow. Is this what you guys hear when the piano is out of tune? I'm not use to hearing it.
I mean, I can hear when a piano is obviously out of tune (i.e the piano which I used to record my compostion), but when it is this subtle, I cannot hear the difference.
Regarding out of tune, this is how I see it: If all 3 strings of a tone are unisono you hear a straight tone. There is a tiny area in which all strings vibrate in forced synchronisation. If a string left that area, you hear a wobbling frequency, at the beginning e.g. very slow, some seconds. With time it gets faster until it is several wobblings per second (for a single key!). I would describe that as getting more and more "colored". If a piano is slightly detuned that way, it does not sound that bad to me, the sound overall is getting warmer instead crystal clear and cold. But if the wobblings get more and more, things get worse.