The PWD jitter measurements look a little suspect to me, after all the talk about XMOS, I'm pretty surprised that jitter would still show up at the outputs. It also shows up in the regular measurements. Pretty surprising how firmware would make a measureable difference.

MK1 does not utilize an XMOS USB solution. I bet MK2 would measure better on all digital inputs too.

I don't know enough about DACs to understand why different firmwares might sound or measure slightly differently. The only thing I could guess they could change with such a small impact on measurements might be something like noise shaping, but you'd think they'd have mentioned that if they actually changed something like that. I really can't give much of an educated guess here. But, really, any code change at all could theoretically slightly alter the D/A process and performance. *shrug*

Thanks for the measurements and all the work!  This certainly confirms a few thing many of us have maintained for awhile.  The PWD via USB always sucked.  Though we don't have XMOS data here, as far as subjective impressions it's better but not best, still behind the other inputs  quite noticeably.

The other observation is that these set of measurements are not sufficient to pinpoint the effects of widely reported subjective firmware differences many of us and many across the country have reported independently from each other.  The potential for placebo and expectation bias is also lower, though never can be eliminated, since all the boxes look the same, they have no glowing tubes or art/woodwork and concern DACs the users have owned for awhile with the newer firmwares often (not always) sounding subjectively worse to owners, both of which work against new toy syndrome as a possibility.

You know, I should post a zip of all my PWD test files, in case people want to look at specific comparisons. I just had way too much stuff to post it all on here. Even then, trying to get DAC measurements for 5 filters and 2 different FWs, not to mention native/upsampling modes, can be pretty mind numbing! There are some tests I missed, but I should at least have RMAA measurements for the different filters. I'll sort through my files in the next few days...hard part is using a simple naming convention that is easy for others to follow without explanation.

I know the filters won't measure too differently in 16/44 or 48, but 24/96 might better show some differences (keeping in mind measurements indicate the "HD" filters don't always match their "SD" counterpart). Then you have to account for whether or not you were using "HD" or software upsampled music files and/or whether or not you were running native mode or using the PWD's upsampling. While I felt the filters themselves were pretty homogeneous sounding and measuring with "SD" audio files (I don't have much "HD" stuff to test subjectively), there's still a staggering number of combinations you can set up with this DAC.

It's kind of like the measured differences with the two firmwares. Some of the slight differences my measurements show are probably just variance/margin of error. Some differences seem to be more consistent and often take place outside the audible band, but even those are slight enough and of the sort where it's hard to look at them and say, "Ah, this shows why I prefer X over Y." Though, maybe someone more of an expert in the area might be able to look at these slight differences and start to guess what might be the underlying cause.

I think PS Audio was going for fairly consistent performance across the digital filters, compared to something like the Audio-GD Wolfson DACs or, slightly, the Gamma2. But, let me dig through my stuff and see if I can't find some identifiable and consistent differences besides the obvious square waves.