So this is a pretty niche question. I am replacing all the tubes in my Lumley M100's . My question is , into what sockets does the 12AX7 and 12AU7 go? I thought it would be easy, just follow what was in my amps already. So, from a birds eye view looking down, the one on the left side was a 12AU7. So I replaced it with a 12AU7. But, the old small tube on the right was a 12AU7 as well. I thought the 12AX7 would go there. So, i don't know for sure which goes where . I wonder if anyone knows?? I just learned that one of the most gifted audio tube circuit designer technicians recently passed, Dan Santoni , who lived in Ontario Canada. He was my go to guy and will be sadly missed. Thanks in advance for anyone who can help.