Apologies to the group if this is off topic--any suggestions if it is??

I bought a second hand power amp and mixer amp on e-bay. The intention was
to use the 100volt line to run a number of speakers around my arena, where I
ride my horses, to practice my dressage to music. I know next to nothing
about 100v systems and I have now found that the company who made the amps
has ceased trading! Does anyone know ANYTHING about "Modular Communications
Ltd" of Telford Road, Bicester, Oxon, UK, or their products. I don't know
how to connect up the amps, either to each other or to speakers. There is a
number of 5-pin DIN plugs on the back of the main amp, but not on the mixer
amp

Any help of any sort would be greatly appreciated. I have all the model
numbers and serial numbers, if this is useful.

Cheers

Steve