Classe CA-201 Issue

Assuming that all the fuses are OK and there is no visible internal damage since you took the unit in for service, Here's a few things you can try.

Swap all speaker, IC and PC's connected to the amp with something else to confirm that you don't have a cable problem.

Plug the amp directly into the wall.

Plug the amp into a wall outlet on a different circuit than it is now. Use an extension cord if you have to.

Undo any recent changes that you made to your system.

There's other things you can try, but I would start with the above first. I thing there's a pretty good chance that something is wrong with the wiring in your house, and you're not aware of it. Maybe a wire is corroded or an animal did some type of damage. The results of this can be that you are getting less power from your outlet, forcing the amp to go into protection mode. Also, it would be a good idea to unplug your amp from the wall, and any cables connected to it, until you are able to locate the cause of your problem. And if it does look like your house wiring is at fault, have someone look at it right away. You can have a fire or do damage to other electrical devices in your house.

I had a Classe CA-300 a while back and I had the flashing green light a few times including at turnon. It turned out this was due to some low-frequency pulses produced by the preamp while it was warming up. It would be easy to find out if your preamp is causing the problem. Simply remove the input cables from the amp and replace them with shorting plugs. If the amp doesn't have the blinking green light, then your problem lies with the preamp or source component. If you still have the blinking light, then you likely have a problem with the amp's internal circuitry.

I always thought it was strange to use green for the warning light and red for normal operation.

I had the same problem and it turned out to be the preamp.

I had a Classe model 15 that would shut down when used with the tube preamp I was using. It turned out to be DC leakage from the preamp. The protective circuits in the Classe amps are super sensitive.

Additionally, I always leave my amp on...

Noah, I concur on DC from your preamp being the possible cause of your amp going into protection.

They are super sensitive. I had this problem with the original CA 200 and it was an MIT speaker cable. I sent it back twice to MIT and they could not find anything wrong with it. They tried to put in a zobel and it still did it. Always occurred several minutes into playback. Had to ditch the SC.

This amp also does not like one of my tube preamps. I still have the amp and I love the midrange bloom.

Did your classe 15 automatically play again. I made the mistake of turning on my tube preamp while the classe 15 was on. I heard a pop through the speakers and now no output from the amp. There is a red light lit on the circuit board. It powers up but I don't here the soft start click and no output. Nothing looks physically damaged inside.
Thanks

Yes it did. As a matter of fact I never had any trouble when I had a subwoofer in my system. It started when the sub was removed.The preamp that is causing your problem must have DC leakage like mine did.