And soundboard response too but I think that hammer density can trump SW (except maybe in extreme cases) and there are many examples of a light hammers on higher tension scales (older Steinway D's and older Bechsteins come to mind) where the they were more than adequate to the task.
David Love
www.davidlovepianos.com
... Some would say
that the SW must be matched to the string tension and scale, and the rest
follows from that.
Vladan
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