Help Classe CA300 flashing Green Light

Queen Overvolt -
I think you may have a DC component coming out of the digital (a new fault in the player). Thet's why you hear the pop when you switch to it; the Classe is DC coupled so it sees that DC & protects itself. The other equipment is not DC coupled so it doesn't have a problem with that.

Means that my theory is apparently incorrect regarding DC coming out of that player. However it still sounds like the Classe is seeing DC on an input - that pop noise & triggering of the protection circuit is telling you something. I am still trying to figure out the whole picture though (?what is connected to what & exactly what this whole system looks like?) so at this point in the troubleshooting sequence a phone call would be the best bet regarding efficient usage of time.
But over the weekend I thought of another thing to try. Reinstall the Classe & put everything back the way that it was originally, except don't plug the DVD player interconnect into the (??Adcom pre/proc is it??) digital input? Make sure the that tuner input still plays. Now switch to the DVD input. Do you still get that pop & triggering of the Classe into protect mode? If so, then apparently something in the pre/proc's digital input section has failed. Could also try this test with a shorting plug inserted into digital input (or a cable with its' tip & ring clip-leaded into a short circuit).