i've always gone all 6l6, and i don't even really know why! i guess it just sounded better to me on the cleans especially, but it wasn't exactly night and day.
which do you use and why?
I mainly use 6L6s, but sometimes I change to EL34s to get different sounds. When using EL34s I use the triode and pull the presence on the lead to get close to the IIC+. The cleans are definitely fuller and more 3D sounding with 6L6s.
Edit: I forgot to add that I'm talking about the Mark IV.
Sitting here thinking some more… I actually use EL34’s in the simul sockets of my Strategy 400. I was looking for more Marshall mids when used as a power amp for wet dry wet.
Want to mention that there is an art to using 6L6's in the outer positions. The sockets run hotter, so I would use colder rated tubes to compensate. Of course I've tried hotter tubes as well...just because I want to hear changes for myself.