I have been talking to Mike Allen of JoLida, Mitch Singerman, Ralph of Atma-Sphere, and others and they all agree that one needs to watch out when using current production Electro-Harmonix tubes (New Sensor is the distributor).  If you are concerned about your tubes, please don’t hesitate to call me and I can test them on my Hickok 6000.  There has been an increasing frequency of these tubes self-destructing and taking out circuits in the equipment itself.  This is not normal.  So far the tubes identified are the EH 12Ax7, EL34, 6CA7, Genelex, and a few others.  I strongly recommend having them tested, or replacing them with brands like Winged C or Ruby.  I am joining with CE Distributing as a dealer so I will be carrying these brands from now on.   I also can get them within 3 business days if I do not have a specific tube in stock.