Disklavier

I have seen several posts on this topic including what velocity 
should be set to but let me ask this.  

I have a MX100A.  When I play a disk (one I create or a Yamaha 
Pianodisc that came with it) it is very loud.  The part I don't 
understand is, if I bang on the keyboard as hard as I can, I can 
never get the volume I am hearing out of the disks.  Don't get me 
wrong.  I don't want it to be loud.  I'm really concerned about the 
disks ruining my machine, really.  I guesds I really have two 
questions: 

1. How can the piano, physically, play louder with the disks than a 
human is capable of playing it?

2. Is it possible I am harming the machine, playing it this loud?  It 
doesn't seem like Yamaha would engineer software that ruins it's 
pianos but considering the first question....

BTY It's ten years old and seems to be in wonderful condition!  

Thanks