Thank you for your reply, I will consider upgrading to Standard...

"[2] In PIANOTEQ Stage, preset loading is limited to parameters that are present in the interface. Presets built with PIANOTEQ PRO can be loaded in PIANOTEQ Standard without limitation."

So you'll need at least Standard

Might be an audio chain issue actually, you'll need a reasonable amount of oomph in the bass section as well as a well-EQ'd/room corrected output stage for it to get closer to an acoustic - but in terms of sound signal, the sonority is definitely there, based on my set up.

In Standard you can adjust the velocity offset per-note by the way, if that is indeed the issue

If I understand correctly, the Stage version can open presets made with the full version.
If anyone would be willing to upload one, I'd be interested in a preset for the Grotrian and Steinway B (which is what I currently have) with the hammer noise slightly increased.

Am I the only one who finds the velocity scaling a bit too light in the bass region?
Compared to an acoustic piano, I get the impression that the bass register is quieter than it should be—it's a very sonorous range, after all.
I don't believe I've found a way to boost just the lower region within Pianoteq itself.
As a workaround, I created a MIDI transformer in Cubase that adds velocity to any note below G3, which works well for me.

All in all, I really enjoy practicing with headphones using either the Grotrian or Steinway B!