Electroharmonix EL34EH worked wonderfully for me and gave additional improvement after I had converted all the small tubes to NOS Amperex and Telefunken.
Rogue Audio Cronus owners........new tubes ??
My wonderful amplifier is approaching its "second birthday" at the end of the year, and I know I'll soon need to consider replacing the original Svetlana EL-34's. What have you guys used ? I love the sound of the amp just as it is, but I wouldn't mind "improved sound" if it can be had by using different power tubes.