From the looks of the amplifier, it would appear to be from the mid 1950's. My guess is that it was used for Movie Theaters or Drive-In Theaters of the day. It might also have been used to provide P.A. duties at a stadium, but my first guess would be for motion picture use. It would sound four times as loud as a 16.25 Watt amplifier! One thing's for sure, it WASN'T intended as a home Hi-Fi Amplifier!
Bill