Tom Sendall mentions amplifiers for musical boxes.  We stand them on
a wooden board about 18 inches by 12 inches by about 1/2 inch thick,
mounted on side rails: just wood of the same thickness glued on edge
to raise the box up an inch or so above the table or whatever it is
demonstrated upon.

This approximately doubles the volume level, even more for snuff box
type instruments, and makes them audible to audiences of up to about
50 in the museum.  May be worth a try?

Regards,
David Evans
Director, Revelstoke Nickelodeon Museum
http://www.revelstokenickelodeon.com/