Hmmm..., Yes, I'd also like to try the 6550EH. I just used the newly relabled 6550C from SED (the company formerly called "Svetlana"). One of the tubes was apparently poorly made and after use for a while, it suddenly shorted internally. It fried several of the parts in my ARC VT-50 when it lit up like fireworks. I'll probably try the EH when my amp returns from an expensive repair. :(
Holos
Holos