Where else are you going to learn stuff like: "During the 'voicing' process, a master 'voicer' makes adjustments to the hammer's resiliency by sticking the felt with a small row of needles to reduce its stiffness, thereby mellowing its tone. To increase the brilliance of the sound, the voicer hardens the felt by applying a small amount of lacquer."
BTW, I'm going to Steinway Hall tonight to hear this. If you're free (and in town), you might want…