1. Reduce the Unison detuning. (To start, try reducing it greatly, to 0 or about 0.11, and then move up.)
2. And\or increase the Direct duration slider setting slightly.
3. These steps alone may be all that you need. If not, try reducing the Soundboard impedance. (Reducing the Unison detuning will, by default, increase the sustain length, since the hammers are by default slightly off. You can correct this too long sustain using several methods, including moving the Direct duration slider to the right--making the hammers more perfect--or by reducing the Impedance.)
4. Reduce the 3 hammer hardness settings if needed.
5. Reduce the hammer noise.
6. Move the mics around. Try the binaural setting and moving the head around. Slightly to the left of center, facing the keyboard, will give you a warmer sound. There's a sweet spot that varies slightly on each preset, but you'll hear it.
7. Work with the velocity settings to get the sound to react to your keyboard and playing in the way that you want.
Coordinating these things takes some trial and error. It's easy to do too much with one parameter instead of getting the several things to work together.
But come to the PianoTeq forum. Always an ongoing discussion, and the developers listen to users and are open to suggestions.