DAC improvements slowing down?

Like I said, they need a better system and trained listeners as well as good quality tracks. I doubt if they had any of these three. The results point to that.

Also, the nature of the jitter is important. If they are generating random jitter, then this is not at all like the jitter in real audio systems. It is usually correlated in some way.

Jitter has three attributes:
1) amplitude
2) frequency
3) distribution

All of these are important and not just one measurement. They all vary with each other.

Steve N.
Empirical Audio

I believe you are familiar with Dr. Kiryu's study jitter detection in humans. His findings were that even trained people could detect less jitter than what the BBC reported.

https://www.jstage.jst.go.jp/article/ast/26/1/26_1_50/_pdf

Where are the scientific studies published by any non-marketing organization showing jitter is detectable even in the sub 200ps range?

It doesn't because it can't be done. It is great to develop an ultra-low jitter device for a feat in engineering, but for sound benefits??? I suspect the dust on speaker drivers has a bigger distortion impact than modern day jitter.

Scvan - until you experience really low jitter, you will not understand. It is never low enough IME. I perform jitter demonstrations at nearly every trade show, as well as contrasting the sound of AIFF, ALAC and FLAC with wav files. Every single attendee hears the difference.

Steve N.
Empirical Audio

I think along the lines of what Mapman said, given my limited experience. My music coming from a PC, when I moved from a previous configuration to having an Audiophilleo in the chain there was a very noticeable improvement. I recently tried an exaSound e22 that has femto clock and it didn't sound better than the Audiophilleo plus Metrum Octave.

Obviously, several factors at play here, not simply jitter, but I was expecting a big impact from the femto clock. Just didn't happen for me.

Lew - I tried a Femtoclock and even designed a module for it with regulators etc. It didn't measure any better than my previous clock module. It may have lower jitter at 20MHz, but this is not important with audio.

Steve N.
Empirical Audio