In various places in Pianoteq, parameter resolution is 1 db; I have found myself needing 0.5 db or even a finer increment, perhaps. Half a db difference is clearly heard on any reasonably good equipment; it would be very nice if Pianoteq's resolution was at least this fine, 0.1 db would be even better (de facto standard for professional audio software).
Can you be more explicit in your request - "db" is a measure of volume and most parameters do not directly control volume. Since parameters can be assigned to midi controllers I would assume that the range of values is limited to 0..127. Perhaps this is what you are referring to.
No, I am not at all referring to MIDI control; I am referring to editing sound parameters that go to make a preset. Here is the list of all the places where finer db resolution (ideally 0.1 db) would be good, it is not long:
Voicing
spectrum profile level of different harmonics
Sound Recording
level of microphones
Volume
It is important that the finer resolution of Spectrum Profile and Volume be available in Note Edit as well as globally.
I do not use the Pianoteq Equalizer or the effects, but for people who do, 0.1 db resolution is probably desirable.
There are other db parameters (noises, for example), but it does not seem to me that finer resolution is necessary there.
I must say I never felt that 0.1 or even 0.5 dB was important while I was tweaking sounds in Pianoteq.
Here is a concrete problem I recently encountered, and there were others: Pianoteq Bechstein has a harpsichord-like sound that naturally suggests baroque music. This led me to baroque tuning (A = 415 Hz). With this tuning the G1 note has a huge "wolf" (don't know why and don't really care to know); it is curable with Spectrum Profile in Note Edit, but I found that the difference between the "wolf" and a nice sharp tone was somewhere within that 1 db which I could not penetrate due to the lack of resolution; it is either a "wolf" or a tad too bland.
Speaking generally, 0.5 db difference in level of whatever is considered (by sound engineers) to be about the limit of what can be plainly heard by anyone; finer differences are also heard, of course, but require attentive listening and decent equipment (also ears vary). This means that someone with a reasonably good stereo system listening to a Pianoteq recording can very well hear/feel the lack of precision inherent in 1 db resolution; certainly I do. Ask any, say, mixing engineer if he would agree to use a console that does not allow less than 1 db adjustments; chances are he'll just laugh at this preposterous suggestion. Adjusting spectrum is quite analogous to mixing. 0.1 db increment is not very necessary by itself, I agree, but it allows 0.3 db or 0.7 db or whatever; and, occasionally, I actually have used 0.1 db increment (in my DAW).