Learsfool, I had the same experience, after rolling all of the tubes in my monoblocks; I quickly put the 12au7's back in.
Primaluna - Rolling pre tubes question...
I'm new to rolling tubes, and have been using the stock 12AU7.
I've a PL Prologue premium integrated with 2 12AU7's per channel. I want to test a new pair(before investing in more), so wondering if front or rear position would best reveal the new tubes character?
Thanks,
Darren