Wow, super interesting. Thank you for sharing.
And this is not a gotcha, I promise. But "He doesn't keep detailed logs of the responses because he said they always show random responses." Would have been nice to see the data. But I see no reason to question the truth of this.
Now. . .(again, I promise, this is not a I gotcha), then why the hell do we care about 100 vs 110 SINAD? This Richard Clark experiment just proved it makes no damn difference. I don't need no Benchmark, nor Hypex, a $400 Sony will do.
Why do we care about 110dB vs 100dB SINAD? I think it's a good question, and I think there are several relevant responses:
1. We don't always care about it. In a really well-performing active speaker with no discernible hiss/self-noise, we don't care about the amplifier SINAD at all, at least not directly. In a power amp, most of us don't care much about 110 vs 100 - both are excellent. In a DAC, however, many of us do care about it because upstream components' noise and distortion will be amplified and further distorted by downstream components.
@amirm has on this basis suggested that a DAC's SINAD should be roughly 10dB better than a power amp's. And if you stick a preamp in between, you have to figure on that too.
2. SINAD and similar measurements are pretty reliable indicators of quality design and internal layout (though not necessarily physical build quality). Yes, you can play counterproductive games with gain and impedance to get a few extra dBs of SINAD out of your preamp or power amp, but most folks here are not obsessed with getting the one very best measuring device - if they were, all the people here who've spent $500-$1500 on Hypex and Purifi amps would instead have spent $3000 on Benchmark AHB2s. Overall it's not simply 110dB vs 100dB that folks are looking at. It's more like the 98dB SINAD, $699 Hypex amp vs the 79dB, $2000 "audiophile" amp. If an amp has 10dB lower SINAD and costs a lot less and/or has more/better features, them maybe you get the lower SINAD one - but if you are playing even CD-quality music, it's not irrational or silly to want equipment whose noise floor can at least match that non-hi-res medium.
3. There is unit-to-unit variation, and so a little extra SINAD can be an insurance policy against your individual unit not measuring quite as well as the one Amir tested.
4. People who believe in objective measurements are still human beings, and sometimes we make irrational or emotional decisions to pay a little extra for better-measuring gear. Other times we pay extra for what we perceive as better build quality. even though we might not actually have any real evidence that the build quality is necessary or will really result in greater longevity. That does not mean measurements aren't useful, valuable, or valid.
Of all these issues, I would say #2 is the most often abused by people who try to criticize the reliance on measurements: the idea that folks here simply chase ridiculously high SINAD is just flat-out inaccurate. It ignores the fact that people also factor in price, build quality, aesthetics/design, features, functionality, and so on - in other words many of the same things that self-identified subjectivists do too.
And I would say #4 is the most misunderstood point: no matter how much you're into measurements, this is still a hobby, it's still about having fun, and we're all human beings who are irrational in some ways. But the fact that we don't always purchase based solely on measurements - and conversely the fact that we sometimes give weight to measured differences that are all beyond the audibility threshold - does not invalidate the science behind measurements, any more than Newton's pursuit of alchemy or interest in Biblical chronology invalidates the mathematical validity of the calculus he co-invented or the utility of Newtonian mechanics.
Oh, and this point actually also connects to your question about why science-based Harman International sells premium gear under the Mark Levinson name. The reason is capitalism: Levinson existed long before Harman acquired it, and it makes money. The fact that Harman sells Levinson gear does not mean Harman secretly doesn't really believe in measurements.
