finalomega

Hey everyone, i own a spider valve mkii hd100 and tonight i let it warm up then flipped the master on and pink looking electricity ran threw my back 4 tubes and now i have no sound. Im not very amp savy at all and I'm not sure if my head is blown or what. 3 of the tubes still light up though, but still no sound which makes me question if the tubes are blown or the head is fried if anyone has any insight or can help it would be greatly appreciated. Thanks