@ampus,
Congratulations to you for obtaining the Octave Jubilee preamp. The Octave Jubillee has been my reference component for a while. You will have many happy listening hours with this unit.
Don’t get caught up in the tube rolling merry go round at first. Listen to the Octave to determine and understand its characteristics before making any changes.
In a previous review of the Octave Jubilee, it mentions that the audio section employs four tubes all of the ECC82 family, and that the E80cc can be used in the input stage.
I responded to you. Hopefully providing some insight on the use of NOS tubes.