I have a Gallien Krueger MB500, purchased about 18 months ago. Today, the amp failed and I cannot find anything on the web that describes this problem. The amplifier produces no sound. The "halo" pilot light that surrounds the on/off switch is dark, even when the switch is pushed in. The "-10 db" switch is lit solid red, whether that switch is pushed in or not. I powered the unit completely off and left it for about an hour, but the same thing happened when I tried to power it back on. There is no weird smell that would indicate fried electronics. I figure that I will have to send the amp back to GK for warranty repair, but I am curious about how serious the problem is.