Hi Chris R, I reread the article by Harvey Rosenberg, Dr. Gizmo on the computer. Chris check out his site, even though he has passed, I think his wife keeps it going. I made a mis-quote. He said to watch out when bi-amping tubes with amps that are push-pull and ones that may be set, or single end triode. Why? Because one uses feedback and the other does not. So solid state bottom end is fine when used with a push-pull amp like the Dyna 70, which uses feedback. I just found the site,I hope it still works..... www.meta-gizmo.com thanks Chris... Mark.