I don't want to beat a dead horse but I'm bugged.

Now let’s play devil’s advocate. When it suits you you will claim -80db is not audible but if a cable was tested and it showed nothing at greater than -90db and Amir said that’s totally inaudible then a 100 audiophiles on this site would be losing their minds. You can selectively accept the measurements you want especially when they are measuring the same thing.

How do you measure in DB the addition of a piece of shungite+copper+graphene on my main comnputer  router? It is my homemade "golden plate"...Or on  the wall socket?

😁😊

These debates are ridiculous not because "measuring tools fetichists" are wrong, they are not even wrong... Like the "gear tasting fetichists" who at least use their ears...

The only meaningful measures in audio are CORRELATED with a listening impressions, it is called psycho-acoutic science...

The rest is only a debate beween Amir and the designer of a Dac for example about a RESTRICTED set of measures and ABOUT THE  DESIGN CONCEPTION  not about his quality sound ...

Because a Dac could have  a sound PERFORMANCE only in a specific room with specific ears and specific system...

 And only acoustic and psycho-acoustic can USE the dac design in real time listening...

When it suits you you will claim -80db is not audible... I expect at high volume in quiet passages it may be...

You would be totally wrong. If I heard any noise I would freak out. All my gear is dead quiet, I work hard to make sure it is. If it’s not dead quiet it gets repaired or returned. I hear zero noise from my Sphinx V3. 80 db were the peaks at certain low frequencies (Class D issues), but most of the noise was minus 100 db.

Those are peaks.

Yes, that is db down, it gets better from there.

@russ69 

 

Those are peaks.

Yes, that is db down, it gets better from there.

It appears it does not get better from there.

But if you happy with it it does not matter. I would be surprised if this was not audible in some manor.

 

Returning to the V3's performance at the loudspeaker outputs, channel separation (not shown) was the same as before, at 60dB in both directions below 1kHz and around 40dB at the top of the audioband. The V3's unweighted signal/noise ratio in the audioband, taken with the line input shorted but the volume control at its maximum, was also the same at 67.7dB left and 66.1dB right, both ref. 2.83V into 8 ohms. This was primarily due to full-wave–rectified, supply-related spuriae (fig.2), though the random noise floor components were also relatively high in level.

 

This was primarily due to full-wave–rectified, supply-related spuriae .

In other words, peaks or spikes that make the measurement seem worse than it is. In this case low frequency spuriae due to class D design. No reviewer, and I must have read a dozen reviews heard any issues in the lower frequencies, nor do I. We can go all night on this. Do you own or have you heard the Sphinx V3? No mater, either has Amir.

In this case low frequency spuriae due to class D design.

 

Can you explain what class D has to do with low frequency spurs?

I don't think anything can make it worse than -66.1db. That seems pretty bad. I did a search on Sphinx. Several users noting noise issues. I did not find anything on the V3.