bmichels . just two suggestions:
if you want to solder the df91 tube sockets pins 4 and 5 together, even when partly disassemling the amp you have about 8mm of space for the soldering iron to solder the pins of the second df91 socket, so the diameter of the soldering iron must be less than 8mm. you should buy and use the smallest one you can find (but maybe you already have one), using my larger one i touched and nearly molded one of this yellow capacitors:
on the left side of the picture you can see the yellow capacitor and the tube socket UNDER this capacitor to be soldered:
and the blue arrow shows the power line to pin 1 of the dl92 tube socket. behind the soldering point and the white cable going to the left is a small 5mm long silver wire going to pin 1, can just be cut, so to summarize the power save and "use 1s4 and 1f33 tubes mod" was much easier to implement than soldering this df91 tube pins.
Edited by GermanGuy - 9/7/13 at 11:31pm