My source apparently is higher than normal, so I'm getting all the volume I need by 9:00 on the knob (Using HD-650's).
Would there be a good place to install a high / low gain switch somewhere in the circuit?
If so, how would you go about doing it?
There are a number of ways of "padding" the input. On this page from VoltSecond's site you are given a number of options for lowering the input voltage before it gets to the tubes:
