Bluthner, so hard to decide !

Interesting.. I dont know why many users not like PTQ Grotrian, I not have chance to play it in real life, but in PTQ, It's pretty perfect to me, all from low to high. It's has own character..

I was re-reading myself....apologies for the lack of clarity (that's what happens when you post in a haste, late at night!).

1.When naming pianos, I was referring throughout to the Pianoteq models, not the real ones
2.My keyboard controller is a Roland FP-80 digital piano
3.to give you an idea of a piano sound I like (with "clarity, weight in the bass and mid, complex overtones in the higher notes": the Rudolf Serkin recording of Beethoven piano sonatas on CBS, I believe from 1963, https://youtu.be/6i9kWrnLf5I). I believe it's a Steinway. The YT sound is quite compressed...but you get the idea.
4. As for the Bluethner, I love the sound overall, but most of the presets seem to have a muffled quality around F2 to A4.The lower range is nice...at low velocities, but the
  overtones come in too fast even with moderate strikes (bark!). Adjusting the velocity curve works...but compounds the middle octaves muddiness. The high octaves have    a beautiful singing quality, but at high velocities, there is a harsh ringing that is hard to avoid. I think the only way to achieve all the "fixes" is to use note-per-note editing in the Pro version. I have the Standard for now...

Well, I gave it a lot of thought and finally decided for the ones in my signature. They pretty much cover the sonic canvas I want.

Doesn't make much sense tying different pianos to different music.  With an acoustic of course, you play everything on the one.  Unless you have more than one.
Usually, you can bet that an indefinitive sound somewhere in the registers can be alleviated by raising the volume, or some other action.
If all the pianos are based on the different models stated by Moddart, then we have to accept different characteristics come in to play.
Just learn to enjoy them; headphones and monitors will need to be the subject of separate tweaking for good results.

Everyone has different tastes, and some folks even commit themselves to playing Steinways exclusively (or bear the wrath of the great marketing behemoth)... but to my ear, Mozart (say) on a Steinway sounds about as grotesque as Debussy on a 1790s Walter, and give me a 1830s Pleyel for Chopin any day of the week, etc etc
I realize that some labor under the notion that the c1875 Steinway-type piano is the ultimate word for all keyboard instruments for all repertoire, but thankfully we have something like Pianoteq available by which multiple historically-appropriate instruments are available for whatever repertoire one might be inclined toward all in one box... why not at least take some of these for a spin and see how a given composer's ideas may have been influenced by the sort of instrument they actually had to work with?

cheers,
dj

I don't disagree, and neither I think would Bach entirely (making exception for his obvious bent toward the "learned" style, vs something like the Empfindsamkeit of his son C.P.E.) as his known preference for music-making at home was the clavichord (which, incidentally, it would be wonderful to have a better model of in Pianoteq than the Neupert we currently have)... but it's simply impossible to articulate Bach's music in the way we know he spoke it on the modern piano, so one ends up making all sorts of "translations" which, no doubt lovely in their own right, objectively take us afield from Bach's actual conception.  For my part, not being possessed of the hubris to presume that my musicianship is in any way even close to being superior to that of Bach's, I prefer to try to listen and learn from the master on his own terms and not that dictated by the sort of translations necessary when using something like the modern piano.  An interesting experiment however is to play Bach on early pianos where one can achieve both coloristic effects and proper articulations... though it's a pity Bach was so dismissive of the Silbermanns he had available to him... if only he'd lived another 20 years or so I think he would have, quite literally, "changed his tune"!

We part ways here, I'm afraid: Bach et al, being indeed truly great, were emphatically composers of their time who demonstrably wrote idiomatically for the instruments they had at hand and, if we're going to play the idle conjecture game, I to the contrary bet they all would have written quite differently for the sort of instruments we have available today...

But we're back in accord here...   We certainly are fortunate to have something like Pianoteq where it's possible to have all these amazing possibilities to try this stuff out for ones self and not be slavishly stuck to just one sort of piano as though it were the end-all-be-all of music making!

Agreed about the B! I had vastly overlooked the Steinway B model. Spent a lot of time on the demo, listened to my wife playing it too (!) and finally purchased it. It is incredibly nuanced and expressive. Some presets need a little push on the bass (on my system at least), that's about it. I keep tweaking my preset for the Bluethner and it's getting there. Interestingly, it doesn't really work for most of my pre-recorded tunes...but when I improvise and adapt to its tone, I really appreciate its massive sound! To be followed...

Perhaps you might post details of your Pianoteq settings and also your audio output system.   I say this as a very satisfied user of the Pianoteq 6 Standard with Blüthner Model One, as well as the Steinway B add-on.   I use a 100+100W Alesis power amplifier,  JBL stereo and sub speakers.   I was pleased with the add-on both before and after buying my 2016 Blüthner acoustic piano.   Perhaps you might review your keyboard calibration,   reduce the Pianoteq default volume and experiment with different dynamic range settings.
Failing that,  enjoy whatever add-ons you choose.
Ian