Shorting pins for balanced input?

Greetings,
My question is two fold. I have a BEZ Q3b preamp with balanced and rca outs. I use a Rawson alpeh J clone which also have balanced and rca ins. Recently I noticed a slight gain drop and thought it might have something to do with the shorting pins Tim included with the amp. Do they have to be used a certain way--pin 1 to 2 or 2 to 3--? The other thing I did was change the 5z4 tube. I don't know what did the change but now the gain is back to normal. Go figure. Great combo but I would like to know what made the difference since I did both changes at the same time. My guess is the tube. Thanks and enjoy the music.