The startup routine is normal. I have had the 7500 for a year or so and it is always the same. Triggers on and then about 30 seconds later the blue light comes on. Mine has always been dead silent on all fronts. Is the hum coming from your speakers or from the amp itself? If the speakers are quiet I would not make any ground connections as indicated above. Check to see if it is the amp case. There are previous threads talking about that issue but I don't know what the resolution is. Crank it up, burn it in and see if it goes away. If not Outlaw will fix it for you.