Saturday 13 April 2024

Detailed THD(+N) vs. Output Level Measurements of ESS ES9039Q2M. Balanced output quality from Hidizs AP80 PRO-X DAP. And Tekton's self-inflicted PR disaster.

Hey everyone, I wanted to post a follow-up of sorts to a couple of previous articles. First, the article "Hi-Res THD(+N) vs. Output Level Measurements (ESS "HyperStream" vs. AKM vs. TI/Burr-Brown). And a bonus R-2R!" was published back in the summer of 2022 showing an interesting sinusoidal pattern in the harmonic distortions with ESS DACs.

Since then, with the release of their newest ES9039 DACs which employ their latest "HyperStream IV" modulator, I thought it'd be cool to have another look...

Another follow-up is a look at the 2.5mm balanced output from the Hidizs AP80 PRO-X Music Player which was measured last year. At that time I didn't do the balanced output measurements so let's capture a few metrics and compare this with the single-ended 3.5mm output.

We can then end off with some audiophile social commentary from this week's drama.

Hi-Res THD(+N) vs. Output Level from ES9039Q2M vs. ES9038Q2M DAC

As you may recall from the previous article, I found something interesting with the ESS DACs which is the presence of sinusoidal variations in the harmonics across output levels when we examine the stepped-sine test closely. For example, here's the output from the SMSL DO100 which features dual ES9038Q2M chips (I see there's an updated SMSL DO100 PRO with dual ES9039Q2M and HDMI now, nice):

We saw this kind of pattern among the HyperStream II architecture chips like the ES9038PRO as well as older HyperStream (I) like the ES9018Q2C. In contrast with the ESS chips, the AKM DACs and TI/Burr-Brown products did not show this pattern.

So, how did the newest ES9039Q2M perform? (Used the E1DA #9039S pre-production DAC as recently measured.)

Notice I put the cursor at -6dBFS and -120dB to show the relative resolution of the DACs; clearly the ES9039Q2M achieving better performance.

Nice to see that the new HyperStream IV DAC does not have that sinusoidal harmonic distortion pattern!

Pretty cool, eh?

Of course, no need to freak out or get too excited... I don't really believe that this sinusoidal pattern was audible with the older generation ES90XX chips given how low distortion is already. More than likely outside of the ability for humans to hear. Nice to see objective improvement in unexpected patterns like this nevertheless across the generations of products!


Hidizs AP80 PRO-X Digital Player - Balanced Output quality

Another quick follow-up is for the Hidizs AP80 PRO-X digital audio player reviewed back in June 2023. It's a nice little portable player which measures quite well (more than good enough for on-the-go listening!).

However I did not measure the balanced 2.5mm headphone output back then so let's have a peek at how it does with a few measurements and graphs.

I. Peak output level & 1kHz 0dBFS THD+N, unloaded

Peak output - Lo-Gain = 2.1Vrms, Hi-Gain = 4.16Vrms

Nice suppression of even harmonics.

With single-ended output measured last year, Lo-Gain = 1Vrms, and Hi-Gain = 2Vrms peak. The balanced output is therefore able to double the output level (+6dB); expected. As discussed previously, balanced headphone output is really about increasing power through "differential drive" (bridging amplifiers); depending on the amplifier quality, there's not necessarily an improvement in distortion or noise level.
We can see that pushing the player to "Hi-Gain" drops our THD+N slightly in this "no load" (to be exact, 36kΩ using the RME ADI-2 Pro FS) condition even though the output level increased by 6dB. 

II. Output impedance

Balanced output impedance is generally about double of single-ended assuming about the same circuit design. As expected then, I'm seeing an increase, measured as just shy of 0.3Ω which is higher than the 0.1Ω with the single-ended 3.5mm phono jack. Good that the impedance is flat across the audible spectrum.

This audio player will have no problem with any normal headphone impedance.

III. 1kHz THD(+N) vs. Level into representative headphone loads

This is meant to be a portable headphone audio player so let's have a look at power under representative headphone-like loads. I used the E1DA Load Board set to balanced mode at 20.5 / 63 / 300Ω for simplicity:

I typically estimate power levels with "hi-fi" distortion threshold at 0.1% THD hence at 20Ω we get 126mW, at 63Ω 153mW, and into 300Ω 58mW. It's a slight improvement over single-ended where into 20Ω I got 98mW @ 0.1% THD. There was a greater gain in the mid-impedance for headphones say between 60-80Ω where at 63Ω we can achieve up to 3Vrms of non-distorted output.

At 1% THD which is how most manufacturers rate their devices, we see 160mW into 20Ω. The official Hidizs specs say 190mW into 32Ω, presumably at 1% THD which is probably consistent with my findings using the lower impedance.


Nothing surprising with the Hidizs AP80 PRO-X (about US$160 these days) balanced output measurements. If you need the extra power, by all means, use the 2.5mm balanced jack with "Hi-Gain". Don't expect any significant lowering of distortion however - 1kHz THD+N at best around -96dB like with single-ended which is excellent for a mobile device.

(For portable balanced headphone output with high-fidelity resolution into low-impedance loads, the E1DA #9039S is the one to beat with better-than -120dB 1kHz THD+N into 16Ω, excellent multitone performance.)


Eric Alexander's Self-inflicted PR disaster...

To end, it was quite the drama this past week with the company Tekton Design and the owner Eric Alexander's hotly litigious threats against those who publish reviews of his products; especially independent objective measurements like on Audio Science Review (the M-Lore speakers) and Erin's Audio Corner. Notice that Tekton doesn't seem to mind less technical reviews like this that challenge underlying core selling points about the purported benefits of the "patented tweeter array" midrange.

Here's Erin's final take on the Tekton Troubadour speakers:

Obviously, it's not the video review itself that was particularly unique (Erin actually enjoyed the speakers, and I suspect it would not have been especially attention-grabbing), but Mr. Alexander's unreasonable approach with his impulsive threats of litigation. He then puts up a YouTube video a few days later saying that he wasn't going to sue anyone with his idiosyncratic view of what he meant by "litigation" (some kind of friendly inter-lawyer chat?), namedropping of Wilson Audio, among other oddities, video since withdrawn. Obviously he must have felt the pressure from the audio community to have backpedaled like this after news of his behavior went public. We might remember 5 years ago there was some brouhaha with a New Record Day's review (long since withdrawn, a summary here of the madness) of one of their speaker models as well. 

It's really good to see that despite all the craziness, frauds, and snake oil in this hobby, there is appreciation from the public that objectivity expressed in good faith is valued. Obviously, actors such as Eric Alexander responding emotionally with bullying tactics rather than engaging at the level of rational objective analysis showing his own measurements or other data is rightly seen as unreasonable, and his actions regressive among those interested in the pursuit of high fidelity. 

The irony to all this is that I don't think any technically experienced audiophile or DIY speaker hobbyist would imagine speakers like the Troubadour would measure without blemish. We might have even been a little surprised that Erin's original subjective assessment was reasonably positive. It's fascinating though that in Alexander's withdrawn video, he focused so much on the impedance graph and the small bump at around 250Hz (box resonance) as if this would have been a major issue impeding prospective consumers' desire for the speaker. Interesting because we're then left wondering whether it's out of personal insecurity that this seemed to be such a psychological injury or his own lack of appreciation for what is or is not meaningful when interpreting measurements!

Furthermore, now we all know that he drills holes through the speaker cabinet and depends on screw-in feet to plug them. 🤔 (Not surprising that plugging these small screw holes only resulted in minor measurement changes for the ported design.)

The only question now is how Tekton is going to move ahead. Since this whole chapter was escalated to public awareness due to Mr. Alexander's self-inflicted words and actions, what's the guy going to do now? He has clearly overvalued the usefulness of the few positive soft YouTube reviews and interviews out there and grossly underestimated the potency of his prideful (something about 18 awards), litigious character with repercussions to his company and those he employs. As the saying goes from Wayne Dyer: "Your reputation is in the hands of others. That’s what the reputation is. You can’t control that. The only thing you can control is your character."
[While I try to keep politics out of these pages it's hard not to make comparisons. I believe this is no different in a much smaller scale of course from a certain prideful ex-president who brings misery to himself and chaos to those around him, and will fail (again) at the elections later this year. Reasonable, conservative-leaning individuals also have limits as to what is unethical and unacceptable in the character of leaders possessing low-quality intellect.]
So, will we see the emergence of a more contrite spirit to rectify Mr. Alexander's image (nobody's beyond redemption, right?)? Will we see measurements for each new speaker coming out from this company as he promised in his retracted video? Supposedly the company has made 250 models in 19 years, a huge number considering a small company - how much R&D engineering time and money went into each one? I guess we'll get a sense based on the quality of the measurements to come, assuming they do come...


Alright audiophile friends, that's all for now. Remember to have a listen to the "High-End" DAC Survey from last week and get me your impressions! Thanks to those of you who have submitted results already.

Enjoy the music...


  1. Great comment regarding Tekton, Arch. Not that I would have ever bought them with their 'Seven Sisters of the Pleiades" tweeter arrangement anyway, but now is my judgement ever set in stone. The only saving grace in all this, is perhaps it puts Amir and especially Erin and their objective testing on everyone's radar now. Hopefully, they'll use the exposure to recruit more individuals to the objectivist camp.

    And you are so lucky to be living in Canada where you can avoid the worst of the 2024 electoral shite show, however it turns out. Let's hope the nightmare ends, finally and forever this first tuesday after the first monday in November, a certain psycho goes to prison for the rest of his natural life, and the US is once again governed like a modern nation instead of some theofascist episode of the Gong Show.

    1. Thanks for the note Phoenix,
      I think things change in waves and the event this week with Tekton is another step towards a more informed and reasonable audiophile hobby that appreciates the importance of objective testing. Even as people like Alexander holds on to some kind of belief that his products presumably are beyond criticism (even down to the molehill of a cabinet resonance).

      Fascinating watching this unfold as we enjoy the music and hopefully beautiful spring where you are. 🙂

      Now as for the political "shite show"... Yeah, I think most of us Canadian neighbors watch with concern. I suppose at one time, the antics were humorous, but these days many of us watch in horror; if we even bother to watch or read the stuff any more other than the end-of-day summaries. Surely, these 2 guys cannot be the best that a country of >300M people can nominate. Not that there aren't problems here in Canada, but comparatively less dramatic and the parties know to strike a center balance. That's certainly a benefit of having more than 2 parties I think. The parties know they cannot act on policies as if the only way to differentiate is to be tempted to take on the polar opposite. Surely, many conservatives can appreciate a "pro-choice" stance on abortion just as liberals can respect the importance of "law and order" such as in Oregon and their response to the last 3 years of decriminalization for possession of drugs.

      Regardless, this will be an "interesting" year and let's hope the nightmare passes in a way that leaves decent people not negatively affected and doesn't add more stress to what the world already faces.

  2. Hi Arch,
    These portable dac/amps are amazing. Quite the achievement given the diminutive size. It is difficult for an audiophile dinosaur such as I, to fully comprehend the advancement in technology that allows such a small form factor to produce both the desired amplification and fidelity. Even the IEM market has, of late, exploded with surprisingly good quality products at very reasonable prices. I suspect there are many enthusiasts that believe size matters when it comes to quality hi-fi equipment. Huge amplifiers by their size alone, must promise wonderful fidelity and naturally justify the mega bucks they cost. Or so one would imagine and hope! Fast forward to the last five or so years and we have several relatively small class d amps, continuously improving and offered at very affordable prices. On April 20th Fosi will launch their V3 monoblocks. 300W for less than many would consider paying for a half decent power cord or interconnect. What a time to be an audiophile!
    I cannot understand the path Tekton chose to defend their product. Erin even asked prior to his review if there were any considerations he should take regarding speaker set up etc. No reply from Tekton. The unfolding saga is a very apt definition of tragedy, a word often misused. To continue in a fashion that is self-destructive without having the self-awareness to realize the probable outcome is tragic. The only way to salvage his reputation would be to grovel and admit to his shortcomings. But as with a certain political candidate that is probably anathema to him.
    I am not especially interested in American politics but the drama taking place over there is fascinating and troubling. How a person of such low morals and documented idiocy could be in the running for the presidency is baffling. Even more disturbing is the fact that there are so many willing to blatantly ignore the obvious and give this narcissistic clown their unwavering support.
    Thanks for the in-depth review, Arch. Take care and enjoy your weekend.

    1. Hey Mike,
      Yeah I think we're fortunate to be living at a time when we're witnessing the commoditization of hi-fi audio (as defined by devices that approach or exceed human perceptual limits) at prices that almost anyone can afford in most audio categories. The sound quality of some of those inexpensive IEMs will easily render very expensive brands simply unnecessary based on objective performance (as usual, luxury/non-utilitarian factors might push one to desire exotic brands). This is a good thing, but threatens the "high-end" industry who hangs their claims on supposedly good "sound quality" yet often objectively isn't particularly spectacular. Beyond audio, I think in the video world we're seeing the same commoditization of quality with 4K resolution, HDR, high frame rates, and "smart TV" functionality...

      Thanks for the note and the tip on the Fosi v3 Mono. I'll keep an eye on it! Looks interesting with the single power supply and auto-standby which would make up for the lack of 12V trigger to turn on/off assuming it wakes up quickly when it sees a signal. Might have to take it for a spin in the soundroom and testbench! I see that it is still based on the TI TPA3255, nothing wrong with that, but I do wonder what comes next.

      I am likewise surprised by the Republican support of Trump; especially among the Christians given the man's obvious moral disrepute. Just because he claims to be a man of faith or aligns himself to certain causes (like abortion? some view of immigration? gun laws?) obviously doesn't mean there's any conviction. At least in my view, one cannot vote for what is so obviously "wrong" and still declare that one has a moral compass. Trump himself and his personality is a "known quantity" and not particularly interesting at this point and I hope people just get tired of it. But the psyche of the followers and the actual numbers of people who might find what he's promising compelling are much more fascinating!

      I was curious about the Trump/Lee Greenwood Bible and ran into this video review the other day. Fascinating, and IMO shameful - not surprisingly.

    2. Hej Arch, That bible scam is yet another in a long line of money grabbing schemes perpetrated by this charlatan. Audioscience were early with a review of the V3 Mono.

    3. Hey Mike,
      Thanks for the link. Interesting. Yeah it looks good overall with the standard 1kHz SINAD we get a very good 94dB RCA, 100dB XLR as far as amps go. More power, but doesn't look like they did anything with the load dependency (ie. that 1dB rise in treble with 8Ω load). Also, the distortion characteristics are typical.

      My sense is that unless one needed the extra power and liked that mono design, from a "quality" perspective, we're basically still looking at TI TPA3255 chip amp quality (like the AOSHIDA A7, AIYIMA A08, and the like).

      While more pricey, I still like the Topping PA5 MkII+ I'm using as my main driver these days.

      What I would love to see is a Topping PA5 MkII+-level fidelity and features (low distortion, nice multitone performance, more benign frequency response, good ultrasonic switching noise suppression, silent ON/OFF, 12V trigger), with the Fosi level of power (200+W into 4Ω, 100+W into 8Ω <1%). I'd be all over that in a heartbeat just to give more ooomph to my main speakers when listening to some hard rock!

      Regarding that Bible. Asking $60 for a print of the public domain King James Version, no references or notes, thin paper, in faux leather in 2024 is a slap in the face to religious conservatives (especially those with nationalistic pride since it probably wasn't even printed in the USA!). Serious scoundrels. IMO, Christians can handle a lot when it comes to trespasses given the message of grace... But this is the most blatant "My house shall be called the house of prayer; but ye have made it a den of thieves" stuff.

      Like I said, I hate to talk politics or faith here, but just like the snake oil of audiophilia, sometimes things are just so obvious and painful. Whether it's for money, or to create allegiance for power, or often both, it's all the same. If one cares about these things, truths need to be expressed.

  3. Suggest you gentlemen stay out of politics. Trashing Trump as a man is easy, particularly if you do not discuss Biden or M. Trudeau. It is not so easy if you look at the results. From my vantage point a country hogwild about promoting suicide is beyond shame or morality .

    1. Indeed, be careful about that one DrK,
      Let's just say some of us are not in that same boat around "promoting suicide" and have been rather successful in putting a halt on certain forms of expansion lately.

      The tide always turns and will in Canada as well - it will be interesting when we have our general election next year. But not to Mr. Trump's extremes nor to that form of character which is the issue, not necessarily his policies nor the general perspective of most reasonable people IMO.

  4. Archi,
    Getting back to the subject, I don't believe Eric A. ever had any real objection to Erin's review, "wheres the beef" I would say. Instead he blew a few minor issues and comments out of all proportion simply as a way to threaten legal action and bully a man who has no real financial power and silence anyone who would dare to say anything negative. He's pulled the same over at ASR only slightly more restrained since IMHO he viewed Amir as possibly having a little more financial power and possible some connections in the legal world.
    But to me the saddest outcome of all this was Erin's statement in that video is that he would have no further dealings with Tekton or Mr Alexander EVER. So the thru the use of his legal bullying tactics he has managed to silence a source of honest objective measurements and subjective opinions. I do hope that he will see the outpouring of support he has earned around the globe and later will decide not to let Tekton scare him or any other honest reviewers off.

    Lastly I was extremely dishearten over your very negative comments towards President Trump. This is just another case of the spread of BS propaganda by the liberals to try and silence the conservatives in the US. For over 8 years now this man has been accused of being everything but the Devil himself but when it comes down to putting up any real evidence their lies turn into mud. Yes we don't all completely agree with the party line, I am pro-choice myself, but that is only one issue of which to be aware. I'm sure you don't agree with everything the liberals try to enforce on it's supporters.
    But when it comes down to the big picture, the US and it's Constitution,
    there is only one best choice for US voters. President Donald Trump.
    MAGA. ;)

    1. Greetings Sal,
      I think you're right, one sad outcome about this episode with Tekton is that it does end up with both sides - Erin and maybe objectivists in general and Alexander - fracturing communications over fear and anger. Hard to know if Tekton ever would have launched litigation or was it just posturing but it's enough of a scare tactic that anyone in Erin's position with a real job and life outside the audio hobby, would not want to deal with the hassles.

      Regardless, I think this clearly has hurt Tekton's reputation by making the issue so public.

      I don't think there's anything to be disheartened about regarding my views on Trump. This is I think a good example of where we can agree to disagree and it needs not affect common viewpoints on many things; including audiophilia!

      Politicians come and go. I'm no fan of Joe Biden - he's obviously too old and of questionable competency. As a doctor, I bet if we had a look at his brain MRI scan, we'd likely have concerns (like with most 80+ year olds). Likewise, I have all kinds of beefs with Mr. Trudeau here in Canada in that I lean more "conservative" in my views of many social and economic issues and I believe here in Canada we've gone too far left including in the academic institutions.

      However, Trump does appear to have some clear challenges when it comes to speaking on "truth" which I think we can all see in various ways. And this deficit is the problem because in order to get things done, parties on both sides need to see the leader be at the very least dependable and reasonable, in a country that prides itself on honesty and freedom to be reflected on the world stage.

      On my browser bookmarks tab, I have CNN, FoxNews, Drudge, and MSNBC; depending on the news item, I might agree with certain news outlets more than others. And to be honest, very often, I find MSNBC's coverage of social issues appalling and often will side with stuff on Fox. Alas, admittedly, usually not when it comes to Trump as president. BTW, I have family in the US who were very much supportive of Trump back in 2016 and 2020. We try not to talk politics too much but I have noticed them moving away from Trump in the last few years even though I know they would want to still vote Republican wholeheartedly.

    2. FFS, Trump is an incompetent narcissist who has his own aggrandizement and survival as his only goals. He tried to prevent a peaceful transition of power on January 6th, he intentionally grossly mishandled classified information, including presenting it to members of his Miami club as a membership bonus, he lied more than any other politician in living memory, he continues to forget who he is running against and otherwise increasingly glitches - and that list could be continued on and on. This is not conservative vs. progressive, this is about the continuation of US democracy and the fundamental safety of the country.

    3. Hey there gzost,
      I hear ya and I agree on many of those points. Which is why I have faith that in November, the Americans will do the right thing if Trump is on the ballot. To me, the question really is, will those who are conservative-leaning see the error of supporting a person such as this (hence my issue with this whole Trump Bible ridiculousness), and at a higher level, can the Republican Party and the right-leaning media see that unwavering support for this man has gone too far? It's late but maybe not too late to change course? I don't think it's healthy for the political system to see the chaos and dissolution in the Republican Party as we're seeing now.

      My hope is that for the sake of all democratic nations (including us in the North), conservatives can see the error of all of this. The cultish idea that Trump was ever going to "save" the nation, or have any power to preserve the Constitution, or at the most extreme even the bizarre QAnon conspiracy ideas obviously taps into certain insecurities within a significant number of citizens. Society needs to hear and discuss with those who are concerned, but IMO, it's important to make it clear in no uncertain terms that this character is more than just flawed. As the Bible fiasco is but another reminder, this is not "a man of God"; and anyone who professes Christian values cannot in good conscience support this. Honestly, if I were a member in a church voting for a leader (pastor, elder, deacon...), would a God-fearing man/woman approve of a nominee found guilty of rape, openly boasts that he "Grab 'em by the p*ssy", is under criminal investigation for "hush money" porn-star payments? Those are just the sexual improprieties. Just like the pure-subjectivist audiophile reviewers who claim "I heard the difference this Synergistic Cable made!", are we to believe Trump when he claims "I'm innocent... This is a witch hunt..."?

      In the words of Sun Tzu: "Wheels of justice grind slow, but grind fine." I think we're gradually seeing that over the last months and this past week.

      Personally while I think it's interesting for the media and citizens to be vigilant about the potential existential crisis and continuation of US democracy with Trump if he were to get elected, I'm not sure we need to fear some kind of "Civil War" as we're seeing in the zeitgeist. Underlying all of this is still that "conservative vs. progressive" tension, and the president isn't all-powerful.

      Anyhow, just some "musings", yet another opinion on the Internet... Will be watching to see how this plays out with interest.

    4. Thanks Arch for the calm and sensible discussion. I agree with you. I live in Las Vegas and as a swing state I'm glad that we "swing both ways" blue and red. I'm leaning more right than many friends, talk and argue about politics all the time but nobody needs to get butthurt.

      Trump needs to go for the sake of the Republican party. He's a liability now. (Joe also needs to go.)

  5. BTW everyone, in terms of "agreeing to disagree", I was contacted by Mark Levinson regarding my article on Daniel Hertz:
    Expensive Audio & Medical Quackery: Mark Levinson promoting Daniel Hertz "C Wave Technology". And the Maria amps. [Including company response.]

    I've added an addendum with company response. Good congenial discussion. Nothing like what has been reported with Tekton.

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