Realistic Sustain

You're obviously the expert here, so this question is more for my knowledge than anything else -- doesn't the Soundboard Impedance setting do what you want here?

Yes that's exactly what it does, but I've found that when you push the impedance too far the tone isn't as natural as what the developers are able to do under the hood.

I checked about 3 presets in each, all very similar within the same instrument.

I've played plenty of NY Ds (they're pretty standard in US halls) and their sustain seems pretty close to my M, likely a little bit longer on average, but I haven't actually timed them. Of course pianos are all voiced differently, so that's a subjective generalization. With this pandemic it might be a while before I play a D again... Comparing the middle and upper ranges would also be interesting, but the bass sustain was immediately noticeable back when I first found Pianoteq, which is what prompted me to test it again in version 7 (I brought it up several years back). I should also add that I haven't noticed much of a difference with other companies' concert grands in terms of sustain, although again I haven't timed them. Most keyboards have a ridiculously short sustain, to the point where it almost doesn't matter if you change the pedal or just hold it down, so at any rate it's refreshing to see Pianoteq moving in a much more realistic direction.

Uhhnn... if you are right, it's quite strange the Beta tests to had missed this, as I supose Modartt listened to people familiar with real NY Steinway-D.
Anyway, it will probably quite easy for them to fix it, and 2 minutes for you download and install the update.

In case some or most people prefer NY-D as it's now, Modartt could (I presume) add some extra presets with longer sustein.

Thank you Nathan for the nice words

We will have a close look. I just made a fast comparison with chord F0-A0-C1 (midi # 29 33 36) played fortissimo (velocity 127) with base presets NY Steinway Model D and HB Steinway Model D, and found that NY lasted longer than HB. Could you give me a couple of examples where you found that NY was shorter than HB?

It's really interesting, I was doing these comparisons in a fairly consistent, quiet, but not silent room, just playing a low C octave with sustain pedal held down (MIDI 24 & 36), somewhere around velocity 120-ish. I then tested a couple of your notes, MIDI 29 & 36, with no sustain pedal and at velocity 127, and found the same results as I did before. I then exported recorded WAV files and brought them into a DAW. If I listened to the tail ends of the sustained notes with the volume cranked way up, I could immediately hear what you heard Philippe, that the NY was indeed longer than the Hamburg. In the long sustained note, the NY has few, or at least very quiet overtones, but a strong fundamental. The Hamburg on the other hand has very little fundamental, but very clear overtones. And the NY does last longer in this way. When I set the volume back at a normal level, I could now just barely perceive the low NY tone about as long as the Hamburg's sustain.

So I think what this might come down to, at least to my ears, is that the Hamburg's higher overtone sustain gives a stronger sense of a longer sustain, while the more pure low sustain of the NY piano gets more quickly lost, even though it's still there. In normal playing I feel like the NY Steinway's sustain is a little unnaturally short, like its momentum just runs out quicker.

Sorry to write so much, but I decided to do another test: octave, MIDI 24 & 36, velocity 127, with sustain pedal down (though having the sustain pedal down or not doesn't seem to change the results too much). It still seemed like the NY sustain was much shorter than the Hamburg. I then exported the audio and opened it in my DAW. Even when I cranked the volume up, it still sounded like the NY's sustain was much shorter, and the level meter confirmed this. The point at which the meter drops below -60 dB is a good 20 seconds earlier for the NY than the Hamburg.

So I think that's what I'm generally hearing, for normal playing, the sustain of the NY Steinway seems to lose energy/amplitude much quicker than the Hamburg (especially somewhere between 20 to 30 seconds in).

(By the way, all of the above tests were done using the same presets as what you used Philippe.)