Hello everyone, a forum newbie here with several questions about an odd scenario with my home theater receiver.  Last Fall, out of the blue my Denon AVR-589 5.1 receiver stopped working.  It would only come on for a few seconds and then resort to Protect mode.  Here’s what I have checked, all resulting in the same outcome, only going to Protect mode.
- I checked all speakers, removing each until none were connected to the receiver.  Power up, right to Protect mode.
 
- I followed the recommended reset procedure with no change.
 
- I upgraded the power strip the receiver plugs into.
 
- I tested the receiver by itself in other outlets around the house with no difference in operation.
 
- I played with other electrical loads in the house, taking them on and offline and testing the receiver in different scenarios.
 
- I checked the power quality with regard to EMF interference and added a system of plug-in EMF filters (GreenWave).  The millivolts of static on the lines was reduced but otherwise no change for the receiver.
 
- Bought a new home theater receiver, Sony STR-DH790  7.1 and plugged it in, without speakers attached.  No change.
 
- I had the local utility check line voltage at my meter.  Each of the two power legs read 118V, within allowable parameters.  They will be installing a 48-hr recording meter on the power in the next few weeks to watch usage etc. to see if anything odd shows up.
 
I haven’t called an electrician and don’t know yet, whether this is a voltage or frequency problem.
All other electronics in the house work as they should.  Any ideas??