[Puma Cat]

Originally Posted by Antonmb

But Stephen, is it relevant if the sound quality is exceptional and noise level inaudible? It’s the end result that matters. Measurements are important, but they never tell the whole story. In the end it’s whether and how they impact the listening experience.

Reall good points, Tony, and I agree with you. Measurements don't always tell the whole story.

Back in the day, lots of folks thought that transistors amps had "exceptional sound quality" and were superior to tube amps. But wait..why did I find a Dyna ST-70 to be more enjoyable and engaging than an H-K Citation 12?

So, what we thought of as "exceptional sound quality" is, we've found over the last 40years or so of high-end...is continually evolving.

We still have folks that believe that with respect to digital music, that "bits are bits", its just 0s and 1s; there's no way that an Ethernet cable (used to be USB cables, remember?) can impact sound quality. We now know this is to be B.S. And, it's not 0s and 1s in digital music reproduction; its analog voltages. We've found that "perfect sound forever" is simply not true.

The impact of high-source impedance leakage current causes increased noise on the ground plane, increased threshold jitter and timing errors in the flip-flops and PHYs in endpoints and the DAC chips themselves, and in the digital domain, timing errors in the nanosecond range is audible. High-source impedance leakage current are an intrinsic failure mode from SMPS.

For an in-depth white paper on this by John Swenson, who designed these digital chips in his professional career, check out this white paper: https://tinyurl.com/yylwak9b

Quoting John Swenson: "Most all network systems used with audio use switching supplies (SMPS) to power the digital devices, routers, switches, computers, etc. The high-source-impedance leakage current from the SMPS will travel through the network equipment, the Ethernet cables, the end-points, and into the DAC where they will create noise on the ground-plane, and thus jitter in the DAC circuitry. Leakage currents can also cause clock modulation in intermediate devices such as “streamers.”

I'm asking a really simple question: do they know about this failure mode from SMPS and are they mitigating it? Are they even measuring it? Because how to meausure it is not obvious, nor is it easy to do. And, it does have an impact on digital music reproduction.