Mesa tube question
Hey guys, I got a Mark V a week ago and one of the tubes was dead. I talked to Mesa and they sent a new pair of tubes which arrived today. The match group on them is GRN. The rest of the tubes in the amp say the same thing. I really don't know much about all this, so my question is: Do I need to change a pair of tubes or do I only replace the dead one and keep the other new one as a spare?