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What am I not understanding?

I recently listened to an Ayre Codex, which I liked the sound of. 

But I'm scratching my head over the measurements at Stereophile of DACs. 

For example, Fig.7 Ayre Acoustics Codex, 16-bit data, spectrum of 50Hz sinewave, DC–1kHz, at 0dBFS into 100k ohms (left channel blue, right red; linear frequency scale)



vs

a measurement for the much less expensive, and recipient of a lukewarm review, Arcam irDAC II

Fig.9 Arcam irDAC-II, spectrum of 50Hz sinewave, DC–1kHz, at 0dBFS into 600 ohms (left channel blue, right red; linear frequency scale)



Note that the second measurement is against a 600 ohm load, which I've seen described as a more challenging load.  I don't know if that's an appropriate statement in the context of these two reviews, though.

Now, it looks to me as if the irDAC is doing a lot better at keeping harmonics well below the noise floor. 

It's not the only measurement where, at least to my eye, the Arcam team is more faithfully reproducing the input signal.  The 16 bit sine wave representation looks much better at defining three voltage levels for the Arcam than the Codex. 

The situation is even more striking for the much more expensive Ayre network DAC, the QX5 twenty

https://www.stereophile.com/content/ayre-acoustics-qx-5-twenty-da-processor-measurements

It seems to roll off high frequencies on CD audio starting well before 20k - it looks about 3 db down at 20 khz? 

The 50 hz tone is a mess, too, yet  at the end of the review "QX-5 Twenty digital hub offers superb measured performance." 

So, my question is this:  do I not understand what the measurements are showing, or are the folks at Stereophile showing the measurements but not choosing not to explain them, because they like the ultimate sound signature in the Ayre gear so much? 

I gather that Ayre's design philosophy is not to incorporate feedback for error correction.

Is this an instance of it being remarkable that the centipede can walk at all, but since Stereophile is known for measuring components, it would look odd if they simply didn't measure components that didn't incorporate feedback? 



 

Re: What am I not understanding?

Reply #1
Now, it looks to me as if the irDAC is doing a lot better at keeping harmonics well below the noise floor. 

Assuming neither DAC is clipping, the second one is a little better, although both are not great by today's standards. 

So, my question is this:  do I not understand what the measurements are showing, or are the folks at Stereophile showing the measurements but not choosing not to explain them, because they like the ultimate sound signature in the Ayre gear so much? 

In terms of how they sound, hearing a 1st harmonic at -70dB is not likely, so while none of those DACs performs very well, they probably do sound more or less similar, or at least close enough that a reviewer isn't likely to notice a problem. 

Is this an instance of it being remarkable that the centipede can walk at all, but since Stereophile is known for measuring components, it would look odd if they simply didn't measure components that didn't incorporate feedback? 

Reading highend DAC reviews is like watching paint dry if looking at paint somehow prevented it from drying.  It is so pointless, it isn't worth the effort.  I assume the point of the review is to find something different to talk about.

 
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