EL 34 vs. KT 88 ---- What's the difference?

Hoosier 1, My 2 cents on your two cents.....I've used every thing in sight on my SFS80, KT90's, 88's, 6550. EL 34's and E34L's. I'm presently using SED 6550's and EI 6922's. Much smoother than 90's and 88's and a bit more life than EL34's. I give a lot of credit for the balance to the EI6922's as well as the SED's. FWIW

Stewie, I think it is not that simple. Different plate voltage and the bias range of the fixed bias circuit both come in to play I think. Just having the ability to adjust bias is not enuf. A user should always ask the manufacturer if use is possible, or at a minimum a knowledgable techie (which I am not) who knows the amp before trying different tube types.

Lance-Baker1, You sound knowlegable. Lead they way. Give us the words.