Best Vacuum tube for Bellari VP129

I've currently got a Ruby 12AX7A tube in, but wondered if there was one that would improve performance noticeably?

bdogsquad11-26-2009 4:18pm

bdogsquad OP Details Discussions Posts This discussion Message User 10 posts 11-26-2009 at 10:21pm Copy Comment URL Report Comment Edit Delete Thanks. I may try that Mullard out. Wonder what the life is supposed to be with these?