Hello tima,
I cut and pasted my response to your similar post on the other thread:
"I do not have the L2.1 Ref, as I posted I have the LL2.1.
The tube recommendations from the Lamm website for the LL2.1 are such:
"
What substitution tube types do you recommend for the LL2.1?
12AU7A:
12AU7, 12AU7WA, ECC82, E82CC, ECC802, 5814, 5814A, 5963, 6189, 6680, 7730, CV491, CV4003, CV8155
6922:
6DJ8, ECC88, E88CC, E188CC, 7308,
the following tubes are manufactured in Russia:
6N23P / 6H23? (cyrillic),
6N23P-V / 6H23?-B (cyrillic),
6N23P-E / 6H23?-E (cyrillic),
6N23P-EV / 6H23?-EB (cyrillic)"
I have read where the 6X4 is pretty much what you are stuck with for that tube, but many use different 12AU7 and 6922 variants.
Just curious and would like to hear from long time users of this preamp as there may be some other options other than factory... or... not.
I appreciate your input and love reading your reviews."
I appreciate your posts and all the input you have given me. You are one of the leaders here that I look up to and have learned much from your work.