Yes, but I think you may need to look at the MIDI driver for that Track. Not the audio driver.
If you are hearing the system sound piano on that track, then PianoTeq is not properly getting the MIDI data and generating the sound to the Audio Driver, instead the MIDI data seems to be going to the basic system synth and then out.

Your explanation seems to say MIDI is going to the basic synth and then out the audio output, instead of going to the PianoTeq synth and then out. Different problem than initially described.

Again, how are you implementing the PianoTeq synth?

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