I thought I'd throw a rock into the pond and watch the ripples... Since no one answered jkilla in the G3 thread, I did. This is the essence of my reply:
Making both triodes the same voltage only works if the emissions are perfectly balanced. I've been fooling around with these little amps for 4 years and unless you have an O-scope, you must balance by ear after you've found the voltage range that gives you a strong, clear sound out of each channel. If anyone, including a headphoneus sanctimoneus, tells you to make the voltage 13.5V on both triodes to bias balance the tube, they don't know what they are doing. I've seen tubes that needed 16V+ on a side to "balance" with ~13V on the other side.
(The following was advice for jkilla from the G3 thread.) If the left side is weak, increase the voltage on that side until the level sounds approximately as strong as the right side. This should also "center" the sound, if what you are listening to was recorded as having such. You could also just have lowered the right side's voltage, but that would probably degrade the sound as well as lower the signal level.
Old radios that used tubes of this nature had to be "tweaked" by their operator to get a decent sound. One of the things they would check was the glow from the tube and how bright it was. They didn't have voltmeters, but they had their eyes and ears. If it sounds right, good or proper to your ears, leave it alone. If it doesn't, keep tweaking. (EDITED for CONTENT)
The stated voltage for a tube is a reference point not an absolute value...
