To misquote Morrissey, some knobs are better than others. The Manley Neo-Classic 300B amplifiers that I've been listening to, for example, have a knob marked "feedback" that goes from 0 to 10. I've learned so much from using it that I've come to believe that if your amp doesn't have such a knob, it should. You see, the higher you set this control, the better the amp will measure. Applying more global negative feedback to these amps lowers their nonlinear distortion and noisefloor, increases their bandwidth, renders them less sensitive to the speaker's impedance variations and otherwise makes them more stable and efficient. In fact, by applying lots of feedback to an amplifier, it's possible to reduce distortion to barely measurable levels.

So what's the problem? Well, a few turns of the knob suggest that negative feedback isn't as useful as it appears on paper.

I've been watching Estelon since they came on the market in the US. Their striking appearance grabs the eye, but, preoccupied with other brands and reviews, I was able to deny them serious attention until now.

I had my reasons—especially price. The prices of those earlier Estelons were a poor fit for my budget. I was also troubled by the fact that, despite rhetoric about driver and component choice, advanced cabinet materials and construction, and fastidious engineering, Estelon has been stingy with details and specifications—not a complete disqualifier but rather a missed opportunity to appeal to objectivist proclivities.

What changed my mind? First, while Estelon is deservedly known for the elegance of its designs, the AURA is, to me, the cleanest design the company has yet achieved . . . Second, at $19,900/pair, the AURA is much less expensive than the earlier models, including the Forza reviewed by Michael Fremer and the XB Diamond Mk.2 reviewed by Jim Austin.