There's nothing unique with the circuitry- it's all the sound of the output transformers. They don't look like anything special either, and their low end is lacking, but wow, what a lively, unrestricted sound they have.
Is the Eico HF 81 really that good?
I read about the little Eico integrated in Stereophile. They said it was incredible. Does anyone here have any direct experience with this unit?