OK, one more measurement
to settle an argument Ted is making that the DS DAC resolves to 20 bits/-120 dB. He shows such an output using Picoscope. That display shows that the output is dwarfed by spurious tones but his graph is very hard to read. So I thought I replicate it using my audio analyzer.
Here is how the DS DAC performs with a -120 dB signal:
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I bet if I did not point out where the 1 kHz input tone is, you would never find it! There are so many spurious tones including a bunch from the power supply that are much louder than the signal itself. This, despite the fact that I used Toslink for input (i.e. fully electrically isolated) and XLR Balanced output (which should be immune to ground currents/noise).
The FFT I use has 256,000 points so lowers the noise floor so don't think that the actual noise floor is that. It is not.
Despite the very low level of our signal, my analyzer is so sensitive it is able to clearly show harmonic distortion, with 5th harmonic being the highest.
No way can anyone with a straight face say this DAC is resolving to 20 bits/-120 dB signal. We don't "watch FFTs." We listen to music and that music is absolutely polluted by distortion and noise well above our DAC.
You want to see how good this can get in a properly engineered DAC? Here is the Matrix Sabre-X MQA Pro again with identical test:
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This is stunningly cleaner! Power supply noise is now below -150 dB and whopping 30 dB or more lower than our signal itself. Harmonic distortion, if you can even spot it, is just the third-harmonic at incredible -165 dB! Our best case hearing dynamic range is 116 dB so you can't hear any of these artifacts. (And can only hear the main tone if you play using 110 dB of amplification.)
Noise floor now (with the addition of FFT gain) is so low it actually falls off the bottom of the graph!
Let's put these side-by-side so the comparison is more clear: (clock on image for larger size)
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How could anyone call themselves "audiophile" yet want to take the DAC on the left versus the one on the right?
It is pure marketing nonsense to say that PS Audio PerfectWave DirectStream (DS) DAC can resolve to -120 dB and hence has 20 bits of resolution.
It does not whatsoever. It reproduces that signal at wrong level (despite the averaging in FFT), surrounds it with tons of spurious tones that are even higher amplitude at it, demonstrates non-linearities in the form of harmonic distortion and has a ton of noise to boot.
And remember, this is at 1 kHz where the DS DAC has its lowest distortion. The highest amplitude signals in music tend to be pretty much in lower frequencies where the DS DAC has worst performance.