Well after over 25 years of playing through GK, I finally had a serious problem with a piece of their equipment. I received my brand new MB500 from RMC Audio on Monday. I finally had a chance to try it out this afternoon. It worked for all of 30 seconds. I hooked it up to my 210 cab, plugged in the SR4, powered it on, and immediately there was a noticeable hiss. This was with the gain and both masters at zero and the horn at-2dB. As I began to address the treble knob to see if it would cut the hiss, suddenly there was no sound other than a steady buzzing. Not a bass sound with some buzzing, just buzzing. Oddly enough, if I depressed the mute button the buzzing got even louder. I tried three different speaker cables and two cabinets, bass plugged in or not, same results. Ugh. I am very disappointed. I contacted GK customer service who recommended I talk to RMC since it was DOA. RMC was helpful and said they will take care of getting it replaced through GK and just to sit tight until I hear back from them or GK tomorrow. Fingers crossed this all goes smoothly and quickly. I like RMC and have dealt with them before and obviously I am a fan of GK so my main reason for posting this is just to vent a little of my frustration at not getting to work out my new purchase. Anyone else have this particular failure right out of the box?