Peevi, I'm not that well versed on audio circuits but a friend of mine was over yesterday and we took the unit apart. He says that the main amp is built into the sub all 700 watts (yours would be higher wattage) and that the receiver is only a preamp. He also found a spare connector on the power supply board that he thinks controls the relay that turns on the amp(in the sub) for service testing. He established that the din connector has 6 pins for the speakers (front left and right, rear left and right, centre and sub) with the ground being the shield on the connector.That leaves two pins for the switching on and off of the unit. We haven't be able to find which pins are which though. I wonder if we took photos of the boards if John might give some insight into what is going on. I don't want to give up yet as it would be nice to get the unit running as a whole.