Shorted AC Supply
Your amp is blowing the House Circuit Breaker:
Do not plug the amp back into the wall under any circumstances, it is extremely dangerous. The main breaker is at least 30 amps.
If you are blowing the breaker with the the amp's power switch off then you have a dead short, probably in the AC cord.
- Open the AC plug if it comes apart, and inspect the wiring.
- If the AC cord is detachable try another one.
- Open the amp and look inside the chassis for any loose metallic objects that could be shorting the AC.
- Look for a broken fuse holder that could be shorting to the chassis.
Before plugging the amp in you will need to be sure that the short is gone by checking with an ohmmeter.