Can't comment on your questions, but here is very good case for the 
clavichord.
https://youtu.be/IL-Pm1HfNyw

On 5/24/2016 1:17 PM, J. Claudio Di Veroli wrote:
> I was today revisiting the epoch-making C.P.E. Bach first Württembergischen
> Sonaten, Berlin 1742. Perhaps not the first post-baroque rococo/classical
> music, but arguably the earliest keyboard masterpieces of the new style.
>
> While the Sonata 1 has only "forte" and "piano" in an idiom that is
> perfectly suitable for the two-manual harpsichord, the Sonata 2 has also
> "pianissimo", with a musical language strongly suggesting the clavichord.
>
> Certainly J.S. Bach (and a few others before him) had prescribed
> "pianissimos" much earlier, but AFAIK not in keyboard scores.
>
> I would be glad to know about music earlier than 1742 with more than 2
> loudness levels, thus clearly showing that the preferred instrument is the
> clavichord.
>
> Best
>
> CDV
>
>
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