What tube amp for starting out?

I am confused of what amp(tube)I should consider as a step up from my ST-70(DYNACO),BROUGHT back to original with modern up to date parts.
I think the sound is very realistic but a bit dead in the mid range.
All other gear is also Dynaco....preamp,tuner.
I AM new to all the many choices now available and love music and want to listen to a presence of the most realism as possible.