REVIEW: Sabaj A20d 2022 Version DAC [Part III] - DSD, Headphone Out, AMPT, Subjective Impressions and Summary. (And some more Peru pictures!)

Okay, we're in the final stretch of my measurements/review series on the Sabaj A20d 2022 DAC. This time, let's finish with some measurements around DSD performance, the headphone amp output quality, and let's talk about subjective listening impressions before the final summary on my impressions of the device. (See Part I and Part II for earlier instalments in this review.)

I. DSD Performance

Over the years, there has been much talk about DSD within the audiophile hobby. The problem is that there's really very little actual native DSD content out there; I guess in a way similar to how in recent years there has been little native, pure analogue vinyl without digital processing. Given the limitations of analogue (generational losses) and 1-bit PDM (a.k.a. DSD, difficulty with editing), this should be of no surprise to most astute audiophiles.

As such, in terms of the relative importance, the ability for a DAC to play DSD well is clearly not high on the list of priorities for most audio lovers IMO. In fact, I rarely see objective reviewers measure DSD performance even though I know a number of audiophiles swear by DSD upsampling of all their PCM material by using software like HQPlayer. I would warn audiophiles to not put too much "faith" in the idea that just because you can upsample to very high rates like DSD256 or DSD512, that this somehow should sound better! I've found that not all DACs reproduce DSD equally well, and excellent PCM performance does not necessarily imply equivalently excellent DSD playback.

Let's see how Sabaj's ES9038PRO DAC takes on DSD material up to DSD512 with the RightMark battery (24/192 source test signal based on maximum DSD specifications of +3.1dBDSD peak amplitude as previously discussed):

DSD analogue filter setting at 47kHz. DSD512* tests done after firmware update; see text.

That looks good overall. For the most part DSD performance is close to the PCM 192kHz from which the test signal was sourced. DSD64 as usual tends to be more noisy with ultrasonic content from noise shaping.

Notice the '*' after DSD512. In my initial testing, I found that there was an issue with excess noise using the original firmware shipped with this unit. I sent the graphs over to Sabaj and they got back to me with an updated firmware that fixed the issue within 48 hours. I'm encouraged to see companies take objective feedback and respond to issues quickly - good job to the technical team at Sabaj. I saw this level of response back in the day with Oppo as well.

For those who have already purchased one of these DACs, keep an eye out for a firmware update on the Sabaj support page which I have not seen yet that improves the DSD512 noise-level performance. I assume the firmware will be incorporated into newer production units.

And here are some 1kHz THD+N graphs using my standard conversion with SoX-DSD using CLANS modulation parameters as previously discussed:

Again, this is good. We're basically looking at THD+N approaching -120dB across the samplerates and DSD256 even exceeding this amount slightly. Great to see DSD performance is consistent like this which means we're safe to use whichever samplerate we prefer unlike the larger variability I found last year with the Topping D90SE (not sure if subsequent firmware updates improved on this).

Here's the 1/10-Decade Multitone 32 at DSD64 and DSD512:

Left channel shown. DSD512 using new firmware that improved noise level.

Looks good. Noise and distortion-free range better than 115dB peak noise (even better if we just look at the 8-sample average).

And for completeness, here are some 24-bit J-Test FFTs to check for typical jitter anomalies:

Given the different modulation technique with very high samplerates, jitter will present itself quite differently with DSD in the form of spurious or low-level noise anomalies rather than sidebands as in PCM. As usual, it's uncommon to see J-Test sidebands in DSD testing with good DACs.

II. Headphone Performance

Moving along, let's have a look at the performance of the Sabaj's headphone output. The company specs indicates that the headphone amp is based on the TI TPA6120A2. As discussed in Part I, the 4.4mm headphone output is actually not balanced, but rather there to provide compatibility. Both the 4.4mm and 1/4" outputs therefore offer a maximum level of around 5.9Vrms at high gain (+8dB) setting (typically, balanced outputs will exceed the single-ended with +6dB).

Company specs indicate a very low output impedance "near 0Ω"; let's measure this:

 

Yup, <0.1Ω across the audible frequencies; basically as low as I can measure!

Now, let's have a look at the frequency response using the dummy loads as well as through the Polk Ultrafit 2000 headphone discussed previously (which has quite variable impedance dipping down to 15Ω and can cause frequency response fluctuations if output impedance high):

Flat frequency response across the dummy and headphone loads; as predicted given the very low output impedance, this is another nice example (like the Drop + THX AAA 789) of a "load invariant" headphone amp.

How about the Distortion vs. Output Level graphs using my typical 20/75/560Ω loads which cover the low/medium/high impedance range?

Tested with both channels driven.

Excellent. I can confirm 1.7W into 20Ω at 1% distortion (official specs say 2W into 16Ω, 1W into 32Ω, consistent with my findings) with both channels. No clipping into 75Ω and 560Ω. Lowest THD+N into the 20Ω load is around -92dB and better-than -116dB with the 560Ω load (specs indicate "up to -120dB" which is consistent with findings here).

Let's look at my 48/960/5472Hz Triple-Tone TD+N at 0.5V into 20Ω:

Better than -98dB TD+N is phenomenal, and even better than my desktop Drop + THX 789 which has been my benchmark over the years scoring -93dB. Very clean, distortion-free headphone amp with a good amount of power to boot.

Finally, a peek at the 1/10 Decade Multitone 32 through the headphones out. Signal also at 0.5V output level:

Other than the 60Hz hum picked up with some associated harmonics, noise and distortions are below -110dB from the peak levels across 8 measurements. Great.

III. Subjective Impressions (and AMPT recording)

Hmmm, that box looks a little different. ;-)
DAC was auditioned in pre-amp mode with direct XLR output to nCore NC252MP amp to my Paradigm Reference Signature S8 v.3 speakers and SUB1 subwoofer.

Ahhhh... After all this technical stuff, how does this DAC sound?

As per my usual procedure, once I unpacked the box and took a few pictures for the review, I stuck the DAC in my main system downstairs and listened for a couple nights, noting subjective impressions, before putting it on the test bench. After measurements are done (usually about 5 evenings or so depending on how complex), I'll stick the device back in my system and listen again. Here are a few albums I've been listening to using the Sabaj and impressions of the sound...

These days, it's not hard to put a DAC into the sound system and right from the start recognize that one has installed a highly "faithful"-sounding component in the chain (you can easily tell when listening to the noise floor, general frequency response presentation, comparisons to other familiar hi-fi gear) - that's the impression I got immediately.

As one who came of age in the '80s, it was a joy listening to Def Leppard's recent Diamond Star Halos (2022, DR6). Definitely a "feel-good" reminder of the old days of big hair and excess all those decades ago!

While production characteristics on the album like the dynamic range follow modern "compressed" sounds, many have commented that this album is a "return to form" for this classic hard rock/pop band. Just turn up the volume on the opening track "Take What You Want" and just cruise with the music!

If you're not into rock, have a listen to Alison Krauss with the boys on their rock/country power ballad "This Guitar" or the straight-up power ballad of "Goodbye for Good This Time" that would have probably been very much at home played on radio stations in the late '80s save for the modern production sound.

Absolutely no problem for the Sabaj A20d 2022 to render the hard rocking tracks, whether bass of the percussion or wailing of guitars in "Kick", and good separation of vocals from instruments (as good as one can get for productions like this). In the top image, notice that I was listening to this album at one point with my Sennheiser HD800 headphones. It sounded great with plenty of volume to spare using these high impedance 300Ω headphones.

Next, let's have a listen to this one:

Ben Harper's Fight For Your Mind (1995, DR9) is one I had not heard of until recently visiting Pacific Audio Fest in late July and the title track was played in one of the rooms as a demo. I thought the sound quality on this track was great and so went home to have a listen on my own system (this is of course one of the benefits of visiting an audio show - getting introduced to music!).

It's a hard album to classify as this 14-track album incorporates elements of funk, blues, some reggae, some folk rock maybe. Lyrical themes of faith, love, and politics. I like the "Shindler's List"-esque melancholy of the extended instrumental intro to "Power Of The Gospel". Check out the initially bluesy "God Fearing Man" which gradually transmutes into psychedelic rock over almost 12 minutes; totally radical, man.

As an audiophile, the sound quality of the production is excellent. Have a listen to the depth of the bass. Harper's vocals are clean, with a nice wide soundstage for the instruments with the voice focused front-and-center (for example "Oppression"). More acoustic tracks like "Another Lonely Day" allows a good DAC like the Sabaj to render the simple instrumentation, highlighting the nuance of each strum of the guitar while Harper's voice sounding intimate as if he's softly singing in front and slightly to the right when I listened using the Sennheiser HD800 (BTW, the headphones which can sound excessively bright significantly improved with DSP filter from Mitch Barnett of Accurate Sound).

I'm usually not a big band kind of guy, but a friend recently introduced me to Gordon Goodwin's Big Phat Band and their album Life In The Bubble (2014, Telarc, DR10) which I only later found out won a Grammy for "Best Large Jazz Ensemble Album".

What a fun album! There's quite a variation of styles here from jazz to blues to funk. Whimsically energetic tracks like "Years of Therapy" are interspersed with the smooth sax of "The Passage". Then there's the Latin rhythms of "Garaje Gato" - make sure to warm up your subwoofer for those drums if you have one. Of course we need some nostalgic big band cool vibes lifted from the early 20th Century like "Why Can't We Have Nice Things". Needless to say, the recording production value is excellent. Soundstage was wide and the listener seated in the sweet spot is treated with the impression of being surrounded by the music. This is clearly a close-mic'ed recording rather than a live performance with a lot of studio work to carefully assemble the parts. This clever studio work helped highlight the excellent rotating soloists.

I love the excellent dynamic "punch", tight transients, and broad range of instrumental parts on "Does This Chart Make Me Look Phat?" (the question a piece of audio gear asked of the objective reviewer after running a frequency measurement ;-). The sound of the harmon muted trumpet solo on this track is awesome. Turn it up - a nice demo track that gives your audio system a workout!

I also plugged in the excellent (but inexpensive) CCA C12 IEM into the headphone port for a listen. The powerful headphone amp meant I didn't need to push the volume beyond 20/99. Output was clean with no buzz or hum (which sometimes I notice with the Drop + THX AAA 789 and IEMs). Excellent detail and transient response with "fast" IEMs!

Finally, with the passing of Olivia Newton-John lately, I thought I'd revisit her album Physical (1981, first release DR13). Ah yes, the early days of aerobics, "athletic" fashion, leggings, lycra and leotards...

This album is a reminder of the "early '80s" sound still firmly in the era of analogue recordings and productions but with the typical pop electric synths of the day (and characteristically cheesy early MTV video). It's got good dynamic range, but compared to modern productions, clearly a lower-resolution sound, mixed with thin, brittleness on those synths, but the recording of the voice sounds good (perhaps a little excess sibilance). Other than the multiweek-#1 title track, there were a couple smaller singles like "Make a Move on Me" and "Landslide" (really strange disturbing video). Beyond the feel-good love songs, the sweet arrangements and lyrics on "The Promise (The Dolphin Song)" and "Silvery Rain" are touching environmental tributes from that era (a time when "acid rain" and the "ozone hole" were making headlines in newspapers).

Regardless of whether I'm listening to the original CD pressing or a more recent remastering (like the Japanese SHM-SACD from 2012), the characteristic sound quality of this album is what it is. IMO, as one who likes a wide range of music, it would be a fool's errand to seek out gear that tends toward "euphonic" rather than simply neutral, transparent, distortion-free sound. A good high-fidelity DAC like the Sabaj simply fulfills that aim by not editorializing the music in any way that prevents the listener from hearing every nuance that's encoded within the digital data (assuming the rest of your system is up to par of course). From this "high fidelity" foundation, as we get to know our own preferences in sound, then we can apply our own EQ or DSP to shape it to what we like. While I appreciate that certain companies "voice" their products, I would much prefer doing what I can to purchase technically clean, neutral-sounding audio products, and then from there "voicing" the system to my heart's content in the soundroom I have.

Speaking of different masterings of music, there are indeed many albums where I think it's important for the audiophile to seek out the best version although I don't think it matters for Physical due to inherent limitations. I applaud Josh Mound and his "The Best Version Of..." work in this regard!

Enough about what I hear. Here's the AMPT recording for your listening pleasure, straight from the DAC output:

Sabaj A20d 2022 (ESS ES9038PRO, XLR) AMPT

IV. Final Summary...

A simple system like this with balanced out from the Sabaj to a little Class D Hypex nCore amp would I bet provide higher fidelity than many very expensive "High End" products out there! Add good speakers of course, a Raspberry Pi streamer, set up a computer server somewhere on your home network, and you're good to go with a very high performance "Type 2" computer audio system! From there, enjoy the music, upgrade speakers when you can, add room treatments as needed. Good to avoid contracting audiophilia nervosa whenever possible, friends. ;-)

It is my belief that modern DACs these days like the Sabaj A20d 2022, based on my listening and technical explorations, have significantly exceeded the potential resolving ability of human hearing already. However, to be true to the spirit of scientific empiricism, I remain open to evidence to the contrary with controlled blinded listening tests.

In the Sabaj, we see a DAC which technically performs at a level which is either at or within a hair's width from other top-of-the-line devices available today. Whether it's PCM playback across the range of sample rates from 44.1 to 768kHz with well beyond 16-bit dynamic range, or excellent DSD playback up to DSD512, this DAC will convert the signal with extreme accuracy.

Furthermore, I was very impressed by the resolution of the headphone output. Achieving up to 1.7W (1% distortion) into a low impedance 20Ω load and almost 6Vrms into higher impedance loads means that this will drive the vast majority of headphones to more-than-adequate levels. With vanishingly low headphone output impedance, this amp will maintain playback consistency regardless of the transducer impedance.

As such, the owner of this DAC can easily put this in their high-fidelity soundroom attached to all kinds of "hi-fi" and "high end" gear knowing that this DAC will supply a clean 2-channel signal with excellent accuracy. While at the same time, confident that it's just as comfortable sitting on a computer desktop as the hub of "head-fi" playback without the need for a separate headphone amp.

[Tip: If I were to use this DAC on the desktop with both headphones and speakers, I would make sure to program the remote Fn button to toggle between headphone and line out since there's no dedicated button on the front. Otherwise one would need to take a few steps within the menu system. Yes, the headphone volume is controlled and remembered by the device independently of the line-level output.]

Finally, if you're like me and have over the years had mainly boxy DACs, the physical appearance can be eye-catching while sporting a nice-sized, color LCD screen providing useful information at a glance, with a conveniently large volume control knob.

Even as audio performance continues to improve to such extreme performance levels on DACs, as discussed in Part I, I do believe that there are paths forward with features and other "creature comforts" to look forward to.

At a current price just around US$400, for the build and feature set, in my opinion the Sabaj A20d 2022 Version represents excellent performance and value for a flagship ESS ES9038PRO-class audio converter.

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With that, ladies and gents, I hope you're having a great Northern Hemisphere summer! And as always, enjoying the music...

I'll end off with pictures from recent travels:

Dead Woman's Pass, Peru - August 2022. 4200m/13.8k feet elevation.

Machu Picchu, early morning just past sunrise - August 2022.

Lone Alpaca, near Arequepa, Peru. August 2022.

Volcan Misti near Arequipa.

Mini stone towers. Mirador de los Andes.

Andean Condor. By wingspan and weight, the largest flying bird in the world. Colca Canyon, Peru.

Finch and cactus flowers. Colca Canyon, Peru.

Finally, not for the faint of heart or guinea pig pet lover, yet still a cultural experience in this part of the world:

Roasted "Cuy". A delicacy of the Incans for centuries. The locals eat it maybe once a month, usually handful of times per year at special events like birthdays. As in many traditional cultures, parts of the animal (like the head) are reserved for the person of honour.
Not much meat but it is quite soft and smooth. Not gamey at all. The very soft parts reminded me of frog.

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Addendum - August 31, 2022:

By request, here are some pictures of the inside:

SMPS bottom right, Bluetooth chips just to the bottom-left (larger chip is the Qualcomm QCC5125 SoC paired with Winbond 16M-bit flash). The large chips are an XMOS XU216 for digital communications and processing (eg. MQA), looks like a MindMotion MM32F103VET 96MHz, 512KB ROM, 128KB RAM, ARM Cortex-M3 microcontroller in the center of the board just below the ribbon cable to the front display (likely handles remote control, screen display, menu settings...).

Spatial separation of power supply, digital, and analogue output sections moving right to left.

A closer look at the ESS ES9038PRO DAC. The larger chip at the top by the headphone out is the TI TPA6120A2; here's a closer look at the headphone section:

Couple of green Nichicon MUSE "for audio" capacitors there (looks like ES series, 16V, 47μF bipolar). And here's a look at the analogue output section (RCA and XLR):

Three TI SoundPlus OPA1612 dual-channel opamps; 1 for each XLR and a single for stereo RCA. I had a look under the board and soldering looks clean as well. Overall looks good.