Need help related to Classe 301 and grounding.

Kind of long , bare with me please.

Upgrated from a Rotel to the Classe. 1st night of hookup there was a spark and the amp blew. No power light at all would come on after that. Replaced the outside fuse, tried it twice and both times the amp light would blink for 4 seconds then go dead.

Whenver I connected my Integra Research RDC-7 to the Rotel via interconnects whether balanced or single ended there was a very loud hum. A cheater plug solved the problem.

When connecting to the Classe there was not a hum , but a mild buzz in the speakers.

Now I recieved this on a Thursday night and fugured I would hook it up quickly {Bad idea}

After playing it for while I decided to put a cheater plug on it and the buzz was gone.

Later that night I moved it back in the cabinet with the power off. One of two things happened , either speaker wire touched each other or the cheater plug supplied an incorrect voltage.

When I recieve the Unit back from Classe , I do not want to rerun the blowout.

Now Classe in the manual says do not use a cheater plug {lift the ground} or it can cause a shock. Read this of course too late.

They also say in the manual that ideally it should be a few feet away from the preamp, loose cables , turntables etc. or it may pick up a hum.

So my dilema is when I get it back If I get a buzz Id be crazy to put a cheater plug on it. Now I can move the amp to the other side of the cabinet away from most of my constantly running electronics. I will be connecting the Amp with XLR connections. I thought I read somewhere once there was some sort of isolator that can go between XLR cables that may rectify the problem if it occurs.

My question boiled down is, Are cheater plugs definetly out, Id say yes. Has anyone used some sort of XLR isolator.
does it degrade a signal in anyway? And what can you recommend in general to ensure my Classe provides troublefree performance. By the way The Integra uses a 2 prong outlet and the Classe uses of course a 3 prong outlet. There is no way to reverse the plug on the Integra and this is not a Cable TV issue. Thanks for any feedback.