My first pair of Heresies are from 78, my third is from 78. These are some of my favorite Klipsch, and I could see how they would make great studio monitors.
I run my Heresies on a Scott 222c which is a Quad EL84, and I love it. Gothover recommend the Dynaco St-35, and I can see why. I haven't heard them on a EL34 amp, but could image they would sound great.
That 222c would be tops! The st-35 is a well rounded rockin amp. I used a knight kn724 with el84's for a long time and miss it. That with some h2's was my 1st real klipsch system.