Mark Davis could weigh in about his Davis-Brinton phono preamp work as well.
To keep this in some historical perspective, Mark Davis (whom David Moran mentions in his post) was a more or less 'lone' instance of reason back in the day-- the days when everyone heard everything and anything from preamps and amps, except what they were actually hearing. The
Stereo Review gang (Julian Hirsch, Larry Klein, et al) always argued that any two pieces of properly working electonics would 'sound' the same over loudspeakers, as long as levels were matched. Others, including some at the competing
Audio magazine, and especially the 'undergrounds' (Gordon Holt, Peter Aczel, Harry Pearson, Peter Moncrieff et al) were able to hear all the subjective stuff-- to be fair, the same stuff we've all heard, in our own undisciplined comparisons.
From the manufacturer point of view, David Hafler was probably the most realistic, once admonishing Gordon Holt, telling him that his subjective electronic reports were essentially worthless (Dave didn't say it like that, but that was what he meant). Others, boutique designers (too many to name) realized that as long as they could keep Harry and Gordon in business, they'd likely stay in business, too. So they went along with all the magical nonsense. Did they really believe it? Who can say?
Anyhow, in 1977 or thereabouts, Mark Davis demonstrated that level matching took all the differences away. The general underground response? Everyone laughed at him. They criticized his gear (AR speakers, his homemade 'Davis Brinton' preamp, and a Shure M91 cartridge), saying that these were deficient in the 'resolution' department. Aczel was probably the loudest critic (I think others simply ignored him, hoping he'd go away).
Later, Peter realized that Davis was essentially correct, and he was wrong. I once told Peter that perhaps he was mistaken (I began audio life as a true believer, as most of us did). After all, I pointed out to him that he was using exotic Japanese moving coils, expensive class A amps and preamps, unobtainable MC transformers, and highly touted electrostatic loudspeakers. Peter was not impressed with my argument.
FWIW, and in the context of this ASR review, Tom Holman was also skeptical of Davis' results. He'd worked up a lot of 'esoteric' tests in order to objectively distinguish everything that everyone was 'hearing' in phono preamplification, some published in the AES journal. But in the end it all came to nothing. At the time, Davis reported that Holman's listening methodology was pretty sloppy, but gave him a pass by saying that Tom wasn't a psychoacoustician (Mark had a psychoacoustic lab at MIT, if I am not mistaken).
None of this takes away from Holman's excellent preamplifier. At the time it was an excellent value, and, evidently, once refurbed, it remains so. In fact, it's really a shame you can't buy anything like it for the price, anymore.