John Camille, “Development Notes on a Single-Ended 211 Amplifierâ€,
Sound Practices, Summer 1993 at p. 4:
"I must admit, based on careful listening, that “theoretical nonsense†such as hookup wire construction can and often does have a real sonic impact. The difference between hyper-annealed copper and silver is audible even though the path length is measured in inches. The change is non measurable because it would be buried in the noise at levels 60 to 100 dBV below the noise floor. However this effect shouldn’t be surprising when you consider that many “old time†radio-telegraph operators could pull signals out of the noise even better than the first phase-locked loop detectors which could lock onto a coherent signal buried 20 to 30 dB into the noise floor. The ear/brain interface is a wonderful thing and it is fun trying to fool it with our puny efforts.â€
Paul Joppa, post on Tube DIY Asylum, December 24, 2001 (
http://db.audioasylum.com/mhtml/m.html?forum=tubediy&n=2740):
"I am continually amazed at how much isolation from the power supply is needed. Moving to parafeed has an audible effect, which I attribute at least partly to power supply isolation. But current sources have significantly more isolation than chokes, and are quite audible. This is around 60 dB isolation from a power supply that is already adequately quiet by engineering measurements. And I've heard in the last few months the effect of shunt-regulating the power supply before the current source, and it is still quite significant. This is probably at least 100dB better than what measurement says is adequate. And the latest I've heard is a current source to isolate the regulator before another current source. And it's still a clearly audible effect - we're probably talking 160dB of "excess" isolation now. I have no idea where it will end. As an engineer, this is totally bogus and can't possibly be true. As an audiophile, I hear it and I'll incorporate it whenever I can."
