hifi engine

Rauland-Borg TAX125C power amplifier information

I bought 2 of these amplifiers. They're solid state, weigh a ton and the light comes on on both units. That's as far as I went with the testing. everything but the output is self explanatory. It consists of a modular plug with 9 pins of which only 6 are used. There's also a switch locked in the on position with "trumpet protection" printed below it. So I guess I have a few questions: does anybody have any info on these amps? How is the speaker(s) hooked up? What is trumpet protection? There's 2 Input RCA's, is it stereo. There's also some type of din plug that's tied in to the rca inputs underneath. Several people thought it was some sort of missing tube, but that doesn't make sense. I think it's probably for input switching.
It's construction is beautifully done by hand. I hope someone can enlighten me as to the use and function of this amp.