Disklavier

Another "Newbie" Question:  I downloaded some MIDI files today, which were playing fine on 
the DKV's "acoustic" setting.  When I activated the "Quiet" setting via the Pocket Controller, 
however, I suddenly was hit with a very loud sound blast from the DKV's speakers.   I 
switched back right away, because it was so loud I'm sure I could have damaged the system.  
Any ideas on how I can suppress this?   The Operating Manual does not appear to say 
anything on point.

Our system is the Mark IV, DGC1M4.    The MIDI files, by the way, came from the following 
website: http://www.wtv-zone.com/gnubee/all_piano_midis.   "Carolina in the Morning" is 
one of the songs that reacted this way when I switched to the "Quiet" mode.

Any suggestions would be much appreciated.

Mike