A toast to PGGB, a heady brew of math and magic

[Zaphod Beeblebrox]

2 hours ago, taipan254 said:

Very cool. 
 

I'm excited to hear how folks like DSD vs PCM on ESS and AKM chip based DACs. And how DSD on those DACs compare to PCM on chord DACs. 

I will let others who have been testing comment on their experiences on their ESS/AKM/Chord/R2R DACs. On my AKM based (LIO DAC 2.0 module in Vini Rossie L2iSE) DAC which supports up to DSD512 and offers a pure 1-bit DSD path, I now prefer DSD512 over my previous preference which was 16fS PCM. 

 

All Chord DAC's (with the exception of Chord DAVE) decimate DSD and do the conversion to PCM, so there is not much advantage to using DSD, and PCM would still be preferred over DSD. However, Chord DAVE in DSD+ mode converts DSD256 to 256fS PCM without decimation by applying HF filtering only, effectively bypassing both WTA1 and WTA2 stage and couple of beta testers noticed this had a positive effect (compared to 16fS PCM), but it is too small a sample to draw any conclusions from. Though DAVE also supports DSD512, driver support is not available outside Windows, so, I do not have any feedback on this. Also, DAVE will have to decimate DSD512 to 256fS PCM in addition to doing the HF filtering before passing it on to the next stage, so there is additional processing involved that could negate any positives from the higher DSD512 rate. Finally, I do not think anyone in the beta group had a chance to compare PCM on a Chord DAC (except for Mojo) with DSD on a different DAC, so that may have to wait until later.

 

PS: Currently PGGB DSD is available only for the beta testers, and release is weeks away.

[genefruit]

Will PGGB DSD be sold as a new software solution that is uniquely licensed or will it be part of an update for current PGGB licensees?  If it is included as part of an update, will it be available for licensees at all levels (64,128,256) or exclusive to certain levels?

[Zaphod Beeblebrox]

9 minutes ago, genefruit said:

Will PGGB DSD be sold as a new software solution that is uniquely licensed or will it be part of an update for current PGGB licensees?  If it is included as part of an update, will it be available for licensees at all levels (64,128,256) or exclusive to certain levels?

PGGB DSD will be part of all existing products and there will be a very small increase in cost for new licenses (about $20, only to cover the increased PayPal fee, PayPal increased fee last year for some transactions).

 

I do not believe in charging for upgrades unless I directly incur the cost because of licensing etc. (I had to do this only once before because I had to license high precision library for my needs). There will not be any upgrade fee for existing users, or for new licenses, as the time spent on development was my own which I happily do for my own enjoyment too!

 

PGGB DSD will be available for licenses at all levels:

• PGGB 64bit:  On Windows, PGGB 64bit is exclusive to PGGB-IT! through Audiowise. For Macs, I plan to add a 64bit precision option as PGGB 64 through remastero. PGGB 64bit will support DSD128, DSD256 with up to 7th order modulators.
• PGGB 128bit: Will be available on Windows both as PGGB 128 from remastero and as PGGB-IT! 128bit from Audiowise. Mac version will be available as PGGB 128 through remastero. PGGB 128bit will support DSD128, DSD256 and DSD512 with up to 9th order modulators.
• PGGB 256bit: Will be available on Windows both as PGGB 256 from remastero and as PGGB-IT! 256bit from Audiowise. Mac version will be available as PGGB 256 through remastero. PGGB 128bit will support DSD128, DSD256, DSD512 and DSD1024 with up to 9th order modulators.

All versions will continue to support PCM up-sampling as before at their respective precisions.

[LowOrbit]

I have only one question, ZB, following my positive but limited exposure:

 

Do we get EQ for DSD processing?

 

 

[Zaphod Beeblebrox]

11 minutes ago, LowOrbit said:

I have only one question, ZB, following my positive but limited exposure:

 

Do we get EQ for DSD processing?

 

 

Yes, it is in the works and i expect it to be available upon release.

 

[kennyb123]

6 hours ago, taipan254 said:

I'm excited to hear how folks like DSD vs PCM on ESS

I was most concerned about what would happen in the time domain as what I had heard from DSD upscaling up to this point had been harmful to transients.  What I’ve heard thus far is time domain performance that on most tracks scaled by PGGB to DSD512 is nearly indistinguishable from the spectacular time domain performance I hear from PGGB’s PCM to 16FS scaling.  The PGB-DSD512 improves upon PGGB-16FS by making things sound more natural and easier to enjoy. It’s subtle though probably because the X26pro doesn’t have a pure DSD option.  I must admit though that I’ve only processed a listened to a few dozen tracks.  
 

What’s interesting as well is that I still prefer PGGB-16FS to anything less than PGGB-DSD512x1 (the x1 indicates that it’s done in a single stage, I think). DSD512x1 processing takes significantly longer than 16FS processing.

[Mista Lova Lova]

13 hours ago, austinpop said:

If my early impressions are any indication, this will be worth the wait! 

 

That's exactly how I'm feeling, too. I've had some very limited exposure to the pre-release version of the product and whilst I'll hold off with "tangibles" (direct comparisons of different aspects of sound) until I can do some more listening, the "intangibles" are that I'm hearing a new level of audio quality where it's really difficult to go back to how I listened to music before.

 

In my previous posts, I often wrote about trade-offs, which referred to not only using different filters, but also strongly preferring DSD on my DAC and at the time suspecting that this might be the reason why I would not consider (as in - I would simply not enjoy it) PGGB in its PCM form as my default way of listening to music. Well, it seems to me that I might now be able to close the "Which trade-offs can I live with in the long term?" chapter as PGGB DSD seems to take the best out of everything and then cranks it up to eleven. So far, the only reason (from an audio point of view, so excluding the hassle of doing long and resource-heavy processing) why someone might prefer a different upsampling method that I can think of, is being overwhelmed by how much information (spatial cues, holography etc.) is extracted from music - but that's not a knock against PGGB,; on the contrary, it just shows how good it is at reconstructing the smallest details.

 

Re @kennyb123's impressions of PCM vs DSD - I can agree that in some cases the "tangibles" are seemingly small (in others, very obvious), but, as I've been saying for a long time, in my case there is something about PCM on my DAC (as in - the DAC's internal processing of it) that simply prevents me from full immersion and even PGGB's level of reconstruction was not able to compensate for that, i.e. I felt like the "glass ceiling" was still there (this probably sounds like a seemingly contradictory statement, but using a video analogy - I knew that the resolution of each object was higher, but the grid that they were eventually placed on remained the same, hampering the final result). It's wonderful to be able to experience said level of reconstruction in DSD as I can now fully appreciate what PGGB is doing. And, in hindsight, it also helps me understand my previous experiences - e.g. the gap between PGGB and other filters which I have used, especially in terms of spatial presentation - I would have heard this on PCM too, however I would have been constantly triggered by the "PCM presentation" which I seem to be allergic to and which would have made it difficult for me to focus on all the good things which were happening. Now with this obstacle out of the way, the results are nothing short of spectacular so far.

[kennyb123]

34 minutes ago, Mista Lova Lova said:

Re @kennyb123's impressions of PCM vs DSD - I can agree that in some cases the "tangibles" are seemingly small (in others, very obvious), but, as I've been saying for a long time, in my case there is something about PCM on my DAC (as in - the DAC's internal processing of it) that simply prevents me from full immersion and even PGGB's level of reconstruction was not able to compensate for that, i.e. I felt like the "glass ceiling" was still there (this probably sounds like a seemingly contradictory statement, but using a video analogy - I knew that the resolution of each object was higher, but the grid that they were eventually placed on remained the same, hampering the final result).

Don’t you also have the Gustard x26pro?  To my ears, it’s been an excellent tool to assess PGGB PCM as my participation in the beta testing had me hearing the same benefits as other testers without me ever feeling that I might be missing out.  When other listeners said they felt a particular PGGB enhancement justified reprocessing, I always felt the same.  I’ve only diverged now with PGGB DSD as with the x26pro it hasn’t seemed as it’s moved the needle as much as it has for the others.  My endgame though is the T+A DAC200, and I am

sure that will force me to want to reprocess my entire library.  I will point out again though that my listening to PGGB DSD512x1 has been limited so with more listening my impressions might evolve.

[Mista Lova Lova]

6 minutes ago, kennyb123 said:

Don’t you also have the Gustard x26pro?  To my ears, it’s been an excellent tool to assess PGGB PCM as my participation in the beta testing had me hearing the same benefits as other testers without me ever feeling that I might be missing out.  When other listeners said they felt a particular PGGB enhancement justified reprocessing, I always felt the same.  I’ve only diverged now with PGGB DSD as with the x26pro it hasn’t seemed as it’s moved the needle as much as it has for the others.  My endgame though is the T+A DAC200, and I am

sure that will force me to want to reprocess my entire library.  I will point out again though that my listening to PGGB DSD512x1 has been limited so with more listening my impressions might evolve.

Yes, I do. That's the DAC that I've been doing all my PGGB and HQP testing on.

 

I don't really want to try to convince you that I'm right and you're wrong because I can also imagine why someone might possibly perceive PCM on this DAC as superior (for instance, it comes across as more "in-your-face" which might be interpreted as more punchy, which some people might like; to my ears, it lacks the sophistication of DSD but it's only my perception of it). I would only suggest the following to you - unless there are issues with how the DAC receives the DSD signal as opposed to PCM (in terms of jitter, timing etc. - I don't have the knowledge/expertise to even try to ascertain if there are indeed significant differences here), PGGB in DSD should be at least as good as the DAC's internal modulation, so at the very least there shouldn't be any harm in feeding the DAC DSD. Given PGGB's level of sophistication and complexity, though, I'd say that it's a reasonable inference that, at least on paper, PGGB will do a much better modulation than the DAC's own chip. Question is - is it audible?

 

And that's where each of us might have our own answer. We all hear differently and are sensitive to different things. I have tried many, many times to stick to PCM as this would make my life easier. I always like the first few moments ("punch"), and then quickly lose interest as there's just less depth and holography around each sound. Hence I used to prefer other solutions - they might give me "less" in absolute terms, but they had that naturalness that I craved. And in this sense, less really was more for me.

 

But if I can have both, which seems to be the case, then I couldn't be happier 😀

[Zaphod Beeblebrox]

36 minutes ago, Mista Lova Lova said:

And that's where each of us might have our own answer. We all hear differently and are sensitive to different things

Thanks for your perspective and feedback. A big factor in all of this is that the DAC does not make the system. Even if you both had similar preferences, it is hard to predict the outcome when everything else around the DAC is different. 

 

[kennyb123]

39 minutes ago, Mista Lova Lova said:

And that's where each of us might have our own answer. We all hear differently and are sensitive to different things.

Exactly.  I think also you and I are almost exact opposites when it comes to determining what’s right.  I try to check my brain at the door so I can rely entirely on my ears and emotions.  You have gone about it quite differently, as I would think you’d agree.  I couldn’t agree more though with your conclusion:

 

42 minutes ago, Mista Lova Lova said:

But if I can have both, which seems to be the case, then I couldn't be happier 😀

Amen to that!

[kennyb123]

52 minutes ago, Mista Lova Lova said:

then quickly lose interest as there's just less depth and holography around each sound.

I think this contributes much to why we see things differently.  I could never lose interest over those things being in less abundance.  But if something were to screw with the sound of a drumstick contacting a cymbal, it would be over for me.

 

Another thing I should mention is that the server I’m using underwent an upgrade.  The K50 received the G4 upgrade, which brought a massive improvement.  Holography in particular improved substantially.  I do think PGGB-DSD betters PGGB-16FS in that area but not enough to reprocess all my albums for just that.  Given how important that quality is to you, I can most certainly understand why you would be delighted with the gains in that area.

[Zaphod Beeblebrox]

While DSD is the main focus of the next release, there are significant improvements coming to PCM processing (mainly memory with no change to accuracy).

 

PGGB DSD will support single stage upsampling, and two stage upsampling to the final DSD rate. Single stage (which I prefer) is quite memory intensive and forced me to do optimizations around memory and paging. As a byproduct of the optimizations, 256-bit PCM upsampling of long tracks will now be easier to do even on Macs and it significantly reduces memory requirements without much slow down.

[taipan254]

7 hours ago, Zaphod Beeblebrox said:

While DSD is the main focus of the next release, there are significant improvements coming to PCM processing (mainly memory with no change to accuracy).

 

PGGB DSD will support single stage upsampling, and two stage upsampling to the final DSD rate. Single stage (which I prefer) is quite memory intensive and forced me to do optimizations around memory and paging. As a byproduct of the optimizations, 256-bit PCM upsampling of long tracks will now be easier to do even on Macs and it significantly reduces memory requirements without much slow down.

Will these optimizations trickle down to pggb it? Or are they limited to the main pggb app?

[Zaphod Beeblebrox]

4 hours ago, taipan254 said:

Will these optimizations trickle down to pggb it? Or are they limited to the main pggb app?

PGGB-IT! and PGGB App share the same C++ based processing engine. So yes, the optimizations apply for both.

[Atriya]

The upcoming PGGB DSD release is exciting! Unfortunately my main DAC (Weiss) doesn't do DSD natively, and neither does my Chord Mojo 2.

 

I wonder what a "cheap" NOS DAC to experiment with upsampled DSD1024 might be. The Holo Cyan 2 was recently released at $1200. Apparently Topping will release a 1-bit DAC in Q2 this year, called the D900.

[taipan254]

28 minutes ago, Atriya said:

The upcoming PGGB DSD release is exciting! Unfortunately my main DAC (Weiss) doesn't do DSD natively, and neither does my Chord Mojo 2.

 

I wonder what a "cheap" NOS DAC to experiment with upsampled DSD1024 might be. The Holo Cyan 2 was recently released at $1200. Apparently Topping will release a 1-bit DAC in Q2 this year, called the D900.

I intend to experiment with a Cayin RU7. But that maxes out at dsd256. 

[Atriya]

12 minutes ago, taipan254 said:

I intend to experiment with a Cayin RU7. But that maxes out at dsd256. 

 

Fair enough. I'm just looking for something that can do NOS DSD1024 and isn't a T+A (too expensive).

[seeteeyou]

7 hours ago, Atriya said:

Fair enough. I'm just looking for something that can do NOS DSD1024 and isn't a T+A (too expensive).

 

T+A DAC200 could only handle DSD512 successfully despite the specifications, while Holo May (most likely both Cyan 2 and Spring 3 should be good to go as well) went very well with both 44.1K and 48K families of DSD1024 so far

 

http://erji.net/forum.php?mod=viewthread&tid=2250571

 

https://www.mobile01.com/topicdetail.php?f=348&t=5840425&p=89#87175623

 

Forget about the likes of Denafrips / Musician Audio since they're converting DSD to PCM

 

https://6moons.com/audioreviews2/denafrips/2.html

 

---

 

For the playback side of DSD1024, "Native DSD" is the only way to go and therefore "DoP" ain't getting us anywhere. In other words, macOS is out of the question

 

https://community.roonlabs.com/t/native-dsd-playback-strategy-not-available-on-macos/210711/2

Quote

macOS CoreAudio does not support native DSD playback; it’s as simple as that.

 

---

 

If we don't count any Android-based devices, then it's just a matter of choosing either Linux or Windows.

 

The vast majority of Linux distros didn't come with a kernel that's able to support DSD1024 by default, therefore go for stuff like AudioLinux / Euphony OS etc. unless we wanna apply the following patches on our own

 

http://erji.net/forum.php?mod=viewthread&tid=2283776

https://github.com/zhjie/zhjie_gentoo_repo/tree/master/sys-kernel

 

After that, ALSA should have everything covered

 

https://help.nativedsd.com/en/articles/6948867-playing-dsd-files-on-linux

Quote

ALSA is responsible for all audio related things in the Linux world. ALSA directly supports DSD playback and if DAC does it too, no extra configuration is needed.

 

---

 

For Windows users, it's all about the ASIO driver and here's an example

 

https://www.thesycon.de/eng/usb_audiodriver.shtml

Quote

DSD sample rates: DSD64 (2.8MHz), DSD128 (5.6MHz), DSD256 (11.3MHz), DSD512 (22.6MHz), DSD1024 (45.2MHz)

 

After that, some manufacturers are OK with supporting the 48K family but not the others

 

https://audiophilestyle.com/forums/topic/19715-hq-player/page/470/#comment-855239  

On 8/3/2018 at 5:33 AM, n2it said:

I am pretty disappointed with this response.  I was able to get the latest Theyscon ASIO drivers that support 48k DSD from a Chinese vendor (Topping) in less than one day.   The Topping has an XMOS usb interface, which is the same as in the iFi.   I've also given the documentation from of Theyscon that says this rate is supported by their drivers.  Aren't they the providers of your ASIO windows drivers?  Are they not telling me the truth?

 

Finally it's just a matter of getting the right software player and we've got Column K (e.g. TuneBrowser) on this particular list

 

https://docs.google.com/spreadsheets/d/1rHcXP7PExksxZfkif3Rv2CT1Y_ESpNSv2b0nkKlBySk/edit#gid=1964212797

 

As always foobar2000 should be fine and dandy

 

https://sourceforge.net/projects/sacddecoder/files/dsd_transcoder/

Quote

11/01/20:
Version 1.1.0 - DoP/Native handling simplified, DSD1024 added.

 

https://sourceforge.net/projects/sacddecoder/files/foo_input_sacd/

Quote

02/07/23:
Version 1.5.4 - DSD512, DSD1024 playback fixed.

 

SounDevil

 

http://soundevil.net/download/

http://erji.net/forum.php?mod=viewthread&tid=2252466&page=4#pid34304859

 

Personally I hate a specific piece of software with passion, therefore I never mentioned that.

[LowOrbit]

My T+A Dac200 does DSD1024 without issue, but I don't hear significant benefit from stretching my computing resources that far.

 

It sounds great using HQPlayer and the highest quality DSD modulators at DSD128 or DSD256, so I would not hung up on the numbers.

[seeteeyou]

1 hour ago, LowOrbit said:

My T+A Dac200 does DSD1024 without issue, but I don't hear significant benefit from stretching my computing resources that far.

 

Quite a few firmware updates were released so far, just wondering if you're getting the latest one installed on yours by any chance?

 

https://web.archive.org/web/20231209060213id_/http://updates.ta-hifi.de/firmware/auto_download/DAC200/docs/versions_DAC200.txt

 

Though it shouldn't be done by any end users as shown below, especially when it's a loaner unit

 

https://audiophilestyle.com/forums/topic/63998-ta-dac-200/page/5/#comment-1223743

 

If the latest firmware were still no go for DSD1024, then it might have something to do with the ASIO driver.

 

Not sure if you're running Linux or Windows?

 

---

 

https://audiophilestyle.com/forums/topic/58164-building-a-diy-music-server/page/244/#comment-1274073  

On 3/17/2024 at 10:05 PM, Nenon said:

As we install between 2 and 6 of these per server, I've had thousands and thousands of these Solarflare cards going through my office. I've tried them on several occasions on my server and always had the same experience - my system sounds good with them in the first 20ish minutes and then it sounds worse than the onboard NIC. I have always attributed this to the higher temperature.

 

So I would really advise considering using these only if you have a proper cooling solution.

 

Regarding the SQ of DSD1024, IMHO it should be no surprise that heavy consumption of resources would result in higher temperature and therefore the SQ might suffer accordingly. Wouldn't that seem to be the double-edged sword nature of real-time upsampling then?

 

https://audiophilestyle.com/forums/topic/69046-holo-cyan-2/page/5/#comment-1271952  

On 2/26/2024 at 12:56 PM, dericchan1 said:

I have long given up on pcm. Anyways, to my ears dsd1024 is out of the competition after the first couple of days as dsd256 and 512 are clearly better.

 

dsd256 and 512 are both very good, they sounded different but very close in terms of which one I prefer. Ultimately dsd256 is the winner for me as it sound just a tiny bit cleaner overall (as if the mids are a bit more forward closer to the stage) compared to dsd512 that sounded a bit more “distant”.

 

Another owner of DAC200 also gave up for obvious reasons

 

https://audiophilestyle.com/forums/topic/58164-building-a-diy-music-server/page/242/#comment-1272700  

On 3/6/2024 at 7:42 AM, littlej0e said:

• I largely stopped inline upsampling w/XXXxxxxx because:
  • My DAC (T+A 200) has a built-in native 1 bit DSD DAC that sounds vastly superior to the PCM side. It's not even close. It adds slightly more realism, slightly bigger staging, and far more dynamic rage (especially when playing native DSD files).
  • I discovered dBpoweramp software. I resampled/converted most of my library from 44.1kHz .wave to DSD256 because of the synergy mentioned above. 
    • Running dual Xeon Gold 6148 CPUs on a custom water cooling loop really came in handy. It only took approx. 14 hours to convert approx. 6,000 tracks from 44khz .wav to DSD256 .dif. 
    • Be very careful with this software. It will consume all available system resources and almost melted my rig! 
    • I wouldn't recommend going to all of this trouble unless you have similar native DSD capabilities with a similarly optimized setup. In the end, this is just a "poor man's" way of squeezing better performance out of cheaper gear. Probably isn't worth the hassle for most. 
  • To the surprise of absolutely no one, forgoing upsampling results is lower resource utilization and almost universally better SQ. The same is true when physically decoupling XXXxxxxx upsampling from the DIY Taiko server as well. 

 

Thankfully we're gonna have offline upsampling very soon.

[Zaphod Beeblebrox]

DSD1024 presents challenges even for offline processing in terms of storage size and processing time followed by drivers and some players refusing to play and the USB interface is likely being pushed to its limits. Once you get past these hurdles, even if the DAC specs support the rate, the DAC itself may not perform optimally at the higher rate. 

 

We were able to get DSD1024 to successfully play on couple of DACs. T+A 200 and Holo Audio May and on both occasions, it was on windows (Taiko Extreme). During the testing, one person preferred DSD1024 over DSD512 on May (which may make Cyan2 appealing at its price point), while on T+A 200 one person preferred DSD512 over DSD1024. It is hard to draw any conclusion from such small sample sizes, but I agree that the highest rate DSD a DAC could accept may not always be optimal for SQ.

Note about storage: For the same track duration, DSD512 is the same size as 16fS/32bit PCM and DSD1024 is the same size as 16fS/64bit PCM (i.e. double the size).

[LowOrbit]

7 hours ago, seeteeyou said:

 

Quite a few firmware updates were released so far, just wondering if you're getting the latest one installed on yours by any chance?

 

https://web.archive.org/web/20231209060213id_/http://updates.ta-hifi.de/firmware/auto_download/DAC200/docs/versions_DAC200.txt

 

Though it shouldn't be done by any end users as shown below, especially when it's a loaner unit

 

https://audiophilestyle.com/forums/topic/63998-ta-dac-200/page/5/#comment-1223743

 

If the latest firmware were still no go for DSD1024, then it might have something to do with the ASIO driver.

 

Not sure if you're running Linux or Windows?

 

---

 

I have not updated the firmware on my (now eight month old) Dac200. Never felt the need.

 

I do run HQP on Windows and I use HQP often to convert my PGGB files (in various states of upsampling stored as 64bit doubles) to DSD at 512 or 1024. This is not optimal but sounds excellent. 

 

Now waiting eagerly to be able to take the processing offline and let my HQP computer relax a little.

[littlej0e]

I was able to test upsampling and native DSD on both Linux (EuphonyOS) and Windows (Windows 11 Pro) with the T+A 200. Both fed native DSD files to the T+A without issue. However, HQPlayer upscaling performance was noticeably better on Linux. Both were able to upscale to DSD 1024, but Linux was able to do so using heavier filters and settings without skipping/bottlenecks.
 

This could be due to Euphony leveraging a real-time kernel, or because the ASLA drivers are just better - I'm not really sure. Regardless, the important thing to remember is that upscaling at this level typically requires a CPU with higher clocks, say 5.1 - 5.4GHz, to run optimally. I used an Intel 14900K, but higher-end Ryzen CPUs are likely to work as well. 

 

I discovered that DACs w/true native DSD are very few and far between. In addition to the other DACs mentioned, I believe the Wandala also has native DSD capability, but only up to DSD 256 IIRC. My personal recommendation would be the T+A 200 or the Holo May KTE. I've owned both and prefer the T+A for the extra utility and slightly more engaging sound, but I believe the May is a bit cheaper. YMMV. 

 

As for comparing DSD 64, 128, 256, 512 and 1024 with each other and PCM, that is a highly subjective and very personal choice. I would only caution against using HQPlayer upscaling to evaluate DSD and use native/converted files instead. The differences between in-line upscaled and native DSD can be significant. 
 

Lastly, @Zaphod Beeblebrox, what key features (if any) will PGGB-DSD provide that something like dBpoweramp doesn't (besides being limited to DSD 512)? I am very interested as your PCM version is/was outstanding. 

[Zaphod Beeblebrox]

1 hour ago, littlej0e said:

Lastly, @Zaphod Beeblebrox, what key features (if any) will PGGB-DSD provide 

That is a great question. PGGB DSD is built on the same principles as PGGB PCM which you have indicated you like:

1. (Algorithm) Maximizing reconstruction accuracy using all of the information in the source track and upsampling to the required output rate: In the case of PCM the maximum output rate was up to 64fS. In the case of DSD, the maximum output rate can be 128fS, 256fS, 512fS or 1024fS. So, the upsampling algorithms remains the same as before, just that the output rate for DSD is a lot higher.
2. (Precision) Maximizing reconstruction accuracy using high precision: PGGB PCM supports 64/128/256 bit precision as higher precision helps improve reconstruction accuracy in the audible range. The reconstruction accuracy in the audible range is only limited by bit depth and sample rate. For PCM, for most bit depths higher than 16 bits and sample rates higher than 8fS, 256bit precision helps to deliver the highest reconstruction accuracy in the audible range. With DSD, things are not as clear cut. Since DSD has a bit depth of 1, the amount of information that can be retained in the audible range depends on the DSD rate and also the modulator. Higher order modulators help retain more information in the audible range by reducing the quantization noise, higher DSD rates also provide a larger bandwidth to push the quantization noise out. So, the choice of precision becomes a function of the output sample rate and also the modulator order. There is no point in using higher precision for reconstruction if that information cannot be retained. Which is why for DSD, PGGB DSD uses adaptive precision. From what I have analyzed, 128bit precision works best for DSD rates. 256bit precision is an overkill other than for DSD1024 using 9th order modulator.
3. (Modulators) Minimizing the quantization noise in audible range: In the case of PGGB PCM, I use noise shapers to keep the quantization noise in the audible range as low as possible.  The noise floor is limited by the precision used for computing and also the quality of the noise shaper. For 64bit precision, the limit is about -320dB. If a noise shaper is capable of achieving a quantization noise floor that is lower than -320dB for the given bit depth and sample rate, then it makes to go for higher precision which is 128bit. The limit for noise floor for 128bit (quad precision) is about -690dB. If this noise floor can be breached, only then does 256bit computing makes sense. For PCM, the noise shapers I use can achieve a quantization noise floor as low as -750dB in the audible range, which is why I provide the option of 256bit precision. For PGGB DSD, for DSD 256 and higher, the -320dB limit for 64bit computing is easily breached and for DSD rates 512 and 1024, the quantization noise in the audible range is -400dB or lower with 9th order modulators, which justifies the use of 128bit precision.

There is a cheesy cake analogy I like to give, (forgive me in advance):

1. Algorithm: How good the reconstruction algorithms are, i.e. how well you can predict the intermediate samples. This determines the quality of the cake we baked.
2. Precision: How fine/precise you can get in reconstructing. If you start with a bad reconstruction algorithm, it does not really matter how precise the flawed intermediate samples are! This is like the icing on the cake. If the cake is bad, a good icing does no good!
3. Noise shaping/Modulators: This is the container where you store the cake, it decides how much of that icing you get to keep. If the container is too small, you end up mushing the cake or losing the icing. Too big a container may make the cake wobbly (i.e., there is a limit to how aggressive the noise shaper can be) 

Edit: Since not all DACs/Players support 48k DSD rates, I have also added an inter-rate conversion option, i.e. it will be possible to convert a 48kHz/96kHz/293kHz source track to DSD rates taht are multiples of 44.1kHz. I have tried to do this in a transparent fashion, the Jury is still out on if it is truly transparent compared to 48kHz DSD rates of the same tracks. PCM conversions will also benifit form this for some DACs that are capped at a maximum 44.1kHz rate.