"There is no innovation in stereo amp design in a sense that there isn't any room for it, its based on an hi quality op amp chip that takes and input signal and outputs an amplified signal, the basic formula is still the same in every amp
the difference is the ratio of resistors and caps and inductors used (value ratio which influences RC and LC constants in the cir), quality of components and the op amp chip"
That is a quote from a local friend. We were discussing the Eico HF-81. He basically doesn't understand how an amp with bad measurements could sound good.
Basically, what is truly important in the sound of an amp? I'm not into this side of the hobby but I'm sure there are people here who can answer this (and I'm tired of being asked technical things ).