Have you tried rolling various nos tubes? Can give you more of what you're looking for.
Where next after Eico HF-12's?
I can't seem to break away from these little Eico HF-12's. Mating them with my Reynaud Twin Signatures makes an incredibly inexpensive yet musical system. As the upgrade bug has caught me over the past few years, I've tried other amps. 47 Labs Shigaraki, Rogue Cronus, and some other vintage tube and solid state amps. In all cases, I always returned to the Eico's. My question is this: what do I need to spend to make a significant leap in sound quality? Is it possibly under $2000? I realize the subjectivity of this, but has anyone here been able to happily replace their Eico?