Details of the filters are given in the new version of the manual. See here:

https://www.rme-audio.de/downloads/adi2dacr_e.pdf

I have not studied these in detail, but there would appear to be some differences.

I assumed that it was for the latest version of the DAC as it has a recent revision date (03/21) and the data given for the S/N ratios and THD are different from those in the previous version of the manual (dated 09/19), which I assumed from its date related to the latter AK chipped version. Of course I could be wrong!

the manual is not updated. it's still for the 4493 one.

I don't expect there to be a lot of noticeable difference. Probably the filters are different. The analog headroom may be changed (the 2.5db headroom is a 4493 feature). The "DSD direct" may not be available.

a reasonable move for RME given the akm chip shortage. though i guess the performance should be a bit better than the 4493 version.

internally the the iv conversion circuit may be changed. other parts can remain intact.

No. the 9/19 manual refers to 4490. 3/21 manual refers to 4493. you can refer to sec 31.7 of the manual and see when did RME perform the thd experiment. the 3/21 manual test was done Oct 2019, which was when the 4490 became out of production by akm.

Thank you ning for the insight, I myself don't know nothing about the chip technology, only know some very expensive DAC use ESS chips ....

Here‘s the link to the ESS ES9028Q2M datasheet:

https://www.esstech.com/wp-content/uplo … _v0.41.pdf

There are 3 selectable DAC-filters built in (page 8).

The chip has the option to load custom programmed filters too (last line table page 1):

Page 35 ff. shows the built in filter graphs.

Probably AKM and ESS try to stay head to head in the design race
Anyway we are far beyond what‘s audible, but nice to have such a huge quality margin.

Interesting that the DAC now ships with a Sabre ESS chip, there's potential for even better specs like Topping managed with the D90SE. It'll be interesting what measurements will be squeezed out.

right, probably a close to -120db THD+N would be a reasonable guess.
on the other hand, RME probably has no interest in racing the so-called THD+N leaderboard.
RME designs and sells products that are affordable, and make sense.
You can notice the difference between ADI-2 and other device (be it premium or not) from the moment you turn on the device or insert a headphone jack into ADI-2.
It's just an amazing and unique experience.
Sound perspective ADI-2 has already been perfect since its first appearance in 2016.
I think RME only moves to newer chip when there is availability issue.

Sometimes we think that forums are the center of the universe, but they are not. We are shipping the DAC with ESS for more than 2 weeks already, and not a single customer has released that information. Because most of them don't even write in forums!

The printed manual (version 2.6, online now is 2.7) does not hide this fact. Here is what page 4 has to say:

-------------------
Note about the current ADI-2 DAC

At the end of 2020 a fire destroyed AKM's production facilities for AD and DA converter chips. A resumption of production and thus availability of these components is not expected before 2022. Therefore, many manufacturers - like RME - are forced to either discontinue products based on AKM chips, or to use other chips for the foreseeable future.

The ADI-2 DAC was initially based on an AK4490, later on the AK4493. The current unit uses an ES9028Q2M for its high-quality DA conversion. This chip is very similar to the AK4493 in features and technical specifications, which allows RME to continue offering the ADI-2 DAC in its well-known supreme quality, and with a nearly identical feature set.

Even though this chip is a central (sometimes sole) quality determining element, the ADI-2 DAC is just not a normal DAC. Tech specs and features are based on RME technologies, and they are available unchanged also with the ESS chip:

- Complete DSP functionality (PEQ, Bass/Treble, Loudness etc.).
- All sample rates, PCM as well as DSD
- All digital formats (SPDIF/AES/ADAT)
- Analog input and output circuitry, including Auto Ref and 2.5 dB digital headroom
- Extreme Power headphone output stage
- SteadyClock FS, including the latest 1 Hz filter technology
- Lightning fast sample rate change on playback
- Remote, display, general behavior, operation and handling....

ADI-2 DACs with AK4493 and ES9028Q2M are neither sonically nor visually easily distinguishable. However, the ESS version is recognized by a small C at the end of the serial number sticker (B stood for AKM 4493). Furthermore, the units differ in the available filters. The unit with AKM has a filter called Short Delay Low Dispersion, while the one with ESS has a filter called Brickwall (the other filters, SD Sharp, SD Slow, Sharp, Slow, NOS, are identical). Further Chip dependent differences are mentioned in this manual.
------------------

Regarding Tech Specs: forget the data sheet tech specs. AKM and ESS both have their pros and cons, a simple THD+N comparison won't do it. Additionally we needed to reserve 2.5 dB headroom as that feature of the 4493 DAC should be there as well, and - even more important - the ESS chips do not handle intersample overs as gracefully as AKM chips do. So that headroom is a must - and naturally already steals 2.5 dB of SNR and THD+N.

Reading the manual you might notice the new Loopback feature (mainly for Mac DIGICheck to show playback data) - it will come to all DAC and Pro, don't worry.

And yes, we added all missing filters ourselves by loading them into the ESS chip in real-time.

Happy Music Listening :-)

https://www.rme-audio.de/files/uploads/ … quote2.jpg

I think Matthias's intro already made it very clear --- "Even though this chip is a central (sometimes sole) quality determining element, the ADI-2 DAC is just not a normal DAC. Tech specs and features are based on RME technologies, and they are available unchanged also with the ESS chip"

RME produces products that make sense, and careful engineering considerations are made in their product.
Questions such as why choose chip X but not Y don't really matter.
Practically when implemented well 9028 or 9038 has almost no difference.
It's the RME technology that differentiate it from other products.

cheaper, good enough, and do the job equally well.

Dear Matthias, could you please kindly explain a bit more about the filters when you free?

Thank you ning, are those filters built in and no need to set by the user, so we don't have to care about it at all?

OK, you mean at the setting we can choose one of these filters at a time? and how it affects the output sound? ( I do not know anything about those filter tech at all )

I see, I will try it when the DAC arrives, may be I will ask even more when I get confused .... so, you mean I should start with all filters off at first few days and repeat with different filter playing back same music file(s)?

perhaps you should watch the RME official tutorial: https://www.youtube.com/watch?v=enZD40j-kjI
filter starts at 4:04

it's better you watch the entire 5 episodes to understand how to operate this machine:
https://www.youtube.com/watch?v=fDadqF2 … BXHW8oMCGx

Thanks ning for taking the time! Some corrections if I may:

Brickwall is not part of the ES9028Q2M. Neither is NOS and SD Slow.

NOS  has been implemented as before. It is not true NOS (bypass, no filter) but a highly reduced filter. We even optimized it a tiny bit so that the overshoot seen on the pic in the manual does no longer occur.

Exactly our thoughts. @johannes - read the filter chapters in the manual, they basically answer your questions.

I am a mechanical guy, not understand much about electronics especially audio electronics, BUT, I will try, learning is good thing !

Watched entire 5 episodes, now have a clearer picture of the menu tree..... Many thanks !

Will there be ESS version of PRO, or PRO would stay AKM ?

The ADI-2 Pro FS R BE will not change to ESS. We have enough AKM chips in stock for these units for some time.

I hope that RME use 9028 PRO chip to new RME ADI 2 PRO