You should try the Psvane Art series 12au7s for your Octave preamp. As we both have the same pre, Octave Jubilee, I have experimented with many NOS, including the original JAN, Siemens, and RFTs that Octave specs with the Jubilee. I find the Art series in the Octave Jubilee to be great all around tubes. They do need some good hours for break in, approximately 20-30 hours or so. I use all the same specs for all 4 spots in the Octave Jubilee, including the selected position. While NOS may sound good, sourcing them and reliability issues are detractors to me when I want to listen to music without any disruptions due to tube failure.