Who makes the best Amplifiers

It's subjective, of course, but a few names to throw out there would be McIntosh, Krell, Classe. However, keep in mind that the "best" amplifiers are EXTREMELY expensive, starting at 10k and going up from there. The vast majority of people will be perfectly happy with an Emotiva amp, which are very good and an exceptional value.

That Yamaha is a Receiver not an Amplifier. Are you really looking for a replacement Receiver?

It is a receiver.

Try cutting your speaker wires back and re-strip them to expose new wire. Sometimes a bad wire surface can cause the amp/receiver to go into shutdown.

If that doesn't cure the problem try disconnecting all of your interconnects - including the speaker wires and turn the volume all the way up. If the receiver stays on shut it off and connect the speakers one at a time and re-test. Keep doing this until you find the culprit. It may be a speaker wire that has shorted out - it might be a speaker that is shorted internally. Or an RCA cable.