I meant to ask you, what did you think of Dave's FB loop mods? Were you as impressed as I?
Somehow I missed this post!! After rebuilding my HF-87 essentially stock outside of the HF-89 bias setup, I found it to sound to be good but not great. After making Dave's feedback mods it transformed the amp making it more balanced and listenable over the long term. I just wish I would have isolated my grounds better as it has the normal eico issues with ground loops...
Your project is moving along very nicely and looks amazing! I am looking forward to future posts for more ideas I can apply to my amp.
KC