I thought I might add that I also replace the 180Ohm resistors with Kiwame 2watt/180R soldered in such a way that if a tube goes bad, the solder melts and gravity works as a fuse. In other words, I no longer solder them through the thru holes, but to the leads about 3/8th an inch from the board. (Four of my twelve original resistors scorched the board during my original Svetlana/not Svetlana melt down.) Im not an expert, but I am committed to long term ownership. (Or stuck with it, depending on your point of view.) At least, with NOS RCA black plate 12AU7, Telefunken 12AX7s, the current production Russian made re-badged Tungsol 6550s, and a Jadis DPL pre amp in front of it, it sounds great.
PS: The DPL works awesome with a variety of solid state "back up" amps.
PS: The DPL works awesome with a variety of solid state "back up" amps.