From the look of the unit, and owner's manual, I would say that this is to be used between amp, and DVD player that has a built in decoding function - this is to say, that if your DVD player has 5 channel outputs, then you feed those into the MAD unit, and then tie your amps in from there.
This allows the use of tubes for surround, something that is very uncommon at this point, as far as I can tell.
Looks interesting!