Hi,
here's the beast I'm talking about; this was the whole system as it was on sale in shops in 1993. Click on the amp's pic and you can read that it's digital. It had 3 inputs; one for the disc changer, one for the tuner and one for?? Can't remember. The amp has also an rs232; but for what? Maybe you could ask the owner some questions?

Gretings!