A high end piano, while weighing hundreds of pounds, is actually quite a delicate item. The 2 biggest dangers are swings in humidity and improper servicing.

Humidity:

While high humidity (greater than 70%) can cause inconveniences, such as sticking keys, it rarely causes true damange. Besides, in this day and age most homes that have high end pianos have central air conditioning that keeps the humidity in the summer months at a relatively constant level.

Low humidity (less than 40%) can truly damage your piano. This damage can include soundboard cracks, loose tuning pins, action problems and more.

While maintaining a constant humidity level, say 45%, is desirable, it is difficult to achieve. The most critical step is to put an absolute limit to how low the humidity in the room can go. This usually means carefully tracking humidity with a simple hygrometer, available at most hardware stores, and adding humidity by using a humidifier.

It is best to add moisture to a room, using humidifiers that have a large reservoir to reduce the need to refill and to reduce the chances of going dry for too long. Electrostatic humidifiers, while quiet, have a disadvantage of leaving a white dust. Drum or wick humidifiers need a fan that contributes to noise, but are most effective overall.
Piano Care continued

Voicing is one of the most critical aspects of piano maintenance and repair and perhaps the most mysterious. It’s mysterious because there is so little you can actually specify, unlike the precise measurements of key dip or let off.

Voicing is often referred to as “tone regulating” which has a more clear meaning. It is the technique of adjusting the various parameters that affect the tone of the piano. This of course includes regulation of the action and tuning. But most people consider voicing to be the manipulation of the density of the felt of the piano hammer. It is the image of the technician jabbing a tool with needles into each hammer.

More about voicing...