The action itself should not have a sound of it's own.

"The action itself should not have a sound of it's own - in that regard (in theory) it does not contribute to the tone of the piano at all. However, the action has a HUGE affect on how the pianist makes tone, and anyone who has prepared fine pianos for artists has experienced the difference that apparently non-tonal changes can make to the sound of a piano! Again, these changes do not, in themselves, change the sound of the piano, but they demonstrably will change the ability of the pianist to create the sound they are looking for in the music."

KawaiDon in PW Forums.