Speaking of phono, line preamp and driver tubes, how close a match do we want ?

@inna If the circuit is balanced differential you probably want the balance between internal sections of the tube. Check with the manufacturer on that one.

7% can be easy to meet depending on the tube otherwise. This will matter a lot less if the circuit employs feedback.

 Ralph,

Is the balance between internal sections of the tube more important than balance between two tubes ?

I am not sure about VAC design but don't think Avatar's integrated circuit is balanced. Don't know about feedback.