Negative feedback, voltage and output impedance

One other amp that I noticed that has user selectable negative feedback is the Cary 805C Anniv edition. When I visited the Cary Audio facility, we heard that amp (great sound!) Kirk suggested that we use it w/ feedback set at 0 i.e. disabled. BTW, that's how we auditioned it.

Bombaywalla,
If setting sais @0, it doesn't mean that the negative feedback is 0.
Without one, I doubt that any full range amp is produced. The differential input stages(usually dual triode connected as such) imply the stage with 0 gain and 100% negative feedback. The output stage may than be a feedback free... again, with some degree of sacrifice to load capabilities. With tube OTLs it's simply impossible.

No rule without exception. "The result is that amplifiers with negative feedback will exhibit an unnatural sheen and/or harshness in the high frequencies", Atmasphere says. But McIntosh, to give but one example, uses a large amount of negative feedback in its amps, and still they sound natural and sweet in the highs.

The difference between Atmasphere and McIntosh is that Atmasphere wants to make its product more marketable spreading a gossip that less feedback is always better.

Zero negative feedback on my amp also sounded the best, hands down. Increasing the feedback seemed to constrict the sound, decrease it's palpable quality.