New preamp tube for Einstein with less gain

[Kilian]

Hi,

I´m using an Einstein 100 Head. I think that the Einstein has got so much gain that with another preamp tube I´m able to
push the gain knob on the first channel alot higher to adjust the volume between the three modes(Modding Eini to make the three modes footswitchable)

So my question is:
Which tube must I replace and any recommendations?

Kilian from Germany

 

[Lexicon Devil]

JAN# 5751. It's a reduced output military 12AX7 with 30% less gain than the a regular 12AX7.-- I'm not familiar with the schematic of the amp.