But on the back of the amp there are lights that indicate if there is something wrong with the tubes, none of these are on so the amp should be okay. I think maybe it's the cab. Im not sure they are good friends with eachother... But i don't know. it's so frustrating cause i can't take it back to them cause i bought it online far away. And their enginners have checked it. I got proof of that. I think it's the cab? Maybe i plugged it in the wrong input in the back? Or maybe it's the biasing that needs ajustment.... SO FRUSTRATING!