[joebog1]

After re reading the topic I did some thinking about your concerns for saving EL34/6CA7 output valves should a fault occur. I still use 10 ohm sense resistors on the cathodes, but a very elegant solution to excessive dissipation, is to take the suppressor grid to a supply that is negative.
You already have a negative supply to set bias levels so it is available. After rectification and some filtereing you have a negative supply that you connect to the bias pots (s) to set idle current ( perhaps through a resistor to make setting easier by limiting the bias range) Pin 1 or the suppressor grid of all six output valves may be safely connected to the filtered supply BEFORE it goes to the bias setting pot. ( say minus 60 or 70 volts)
I have ever been amazed that the suppressor grid has been made available for use, yet almost nobody has taken advantage of this feature. The maximum plate/cathode dissipation can then never exceed the maximum ratings of the valve.

Joe