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.

REVIEW: AGPTEK A30X Music Player - inexpensive 32GB utility DAP/MP3 Player. And a few words on EQ and some sample curves.

Open box: music player, quite comprehensive manual, USB-C to A cable, inexpensive earbuds, strap, and lanyard (can be a little tough to snake this through the hole on the bottom right, use a needle or paperclip to push/pull it through the slot!). 

I love my music, which is why I became an "audiophile". I definitely do not believe that audiophiles need to buy expensive or exotic stuff. These days, reasonable sounding products can be very inexpensive and in the service of just having music available on a bus, subway ride, maybe even in a car on a road trip, all we need I believe are "utility"-grade devices to serve that purpose! Lossless is likely unnecessary and hi-res audio would be a waste of storage space on devices like these (let's be honest, hi-res files often are just a waste of space already regardless of device quality!).

With a need for an inexpensive Digital Audio Player (DAP) a few months back, I came across the AGPTEK A30X Music Player as seen in the open box above. With a cost of only about US$30 (bought retail), this little guy features 32GB of microSD storage (expandable to 128GB), has a 2.4" touchscreen, both 3.5mm headphone out plus Bluetooth 5 wireless capability. Furthermore, this supposedly can play video, has an FM radio, can record audio, has a pedometer function, and apparently e-Book reader capability; admittedly I haven't tried all this stuff out nor would see myself using this other than the radio function. This is a self-contained device and does not have WiFi capability.

It supports a range of audio codecs including MP3, WMA, FLAC, APE, and WAV. Up to 24/48 from my testing (like Apple products as far as I'm aware).

Here at the Musings, I think it's just as important running measurements to see how well the "low-end" performs as much as "hi-res" devices! The lowest tier device tested over the years remains the sub $5 CheapDAC'22 😯. As usual on this blog, unless specified, this write-up is in no way sponsored by the manufacturer.

Do bit-perfect digital sources affect a USB DAC's sound quality? [2023 Edition - phone, Raspberry Pi, MiniPC, laptop]

In the image above, we see embedded some pictures of contemporary, expensive (>US$10k) digital audio devices. Each one of these are just streaming or server boxes that can take data over your network or internal storage and pass them along to a DAC with no actual conversion. Typically, these "high end" audiophile products (for example some featured here) are not asked to perform DSP, thus passing the data in a "bit-perfect" fashion. Furthermore, these expensive devices do not include an internal CD/DVD/SACD/BluRay mechanical reader. They're basically computers with hard drives or SSD storage and software to index and manage your music library. You'll typically be connecting them to your favourite external DAC most popularly through USB although proprietary interfaces (eg. Wadax's optical), ethernet, S/PDIF coax/optical, and i2S could be other options.

The other day, a family member was in need of a replacement phone so I gave them my Huawei P30 Pro which I've been using since 2019 and got a Google Pixel 8 Pro. After transferring the apps and data over, I figured I'd try to see if USB Audio Player PRO on the Pixel 8 Pro would work with the very high resolution Sabaj A20d 2022 DAC (ES9038PRO converter) which the Huawei phone previously did not. It worked, reminding me that Android USB hardware and drivers can result in different levels of USB DAC compatibility.

With the phone connected to the DAC, and given that it has been awhile since I've put together a "shootout", let's see if there's any evidence now in the 2020's of potentially audible differences between source devices playing to a very high-resolution USB DAC. Not that I have a $10k streamer lying around here, but a $1000 phone could be different from a sub-$100 Raspberry Pi, right? 😉

[FYI: years ago, I did a test similar to this using various mostly S/PDIF outputs connected to the same ASUS Essence One DAC.]

Let's look at some data.

REVIEW: Hidizs AP80 PRO-X Music Player - touchscreen, unbalanced and balanced headphone output, dual ESS ES9219C DAC. (And time for PAF 2023.)

Digital Audio Players (DAP) are not a class of components I've explored as thoroughly over here at the Musings. However, over the last few years, as smart phones have ditched their analogue headphone outputs opting for Bluetooth audio or (often cumbersome) DAC/headphone amp dongles, what's an audiophile to do when we want to listen to high-quality playback on the go? Perhaps a small DAP can satisfy this need.

Recently, the folks at Hidizs sent me one of their most recent Hidizs AP80 PRO-X (currently around US$200) for an honest review including objective testing of course. This is the 3rd evolution of the Hidizs DAP product line which started with the AP80 in 2018, followed by the AP80 Pro in 2020, and this newest AP80 PRO-X in 2022. As you can see with that picture of the device in my hand, it's a cute, flat, squarish music player measuring only 6.1x5.6x1.4cm, and weighs a mere 70g.

The aluminum and glass body, bright Samsung 480x360 2.45" touchscreen with good viewing angle, contrast and saturated colors, feels sturdy in the hand with convenient volume control knob, and 3 smaller physical buttons on the side.

RETRO-MEASURE: 2006 Apple iPod "Classic" 60GB 5th Generation

Here's a very cool Steve Hoffman forum thread I came across a few months back which "inspired" this post.

I appreciate the iPod. It was quite the gadget back in the day, foreshadowing the rise of touchscreen "gesture" devices. I remember being impressed by the intuitive scroll wheel (introduced in late 2001) which over time transformed to the "touch wheel" by 2002 then the "click wheel" by 2003 and of course "multi-touch" by late 2007 as it joined the family of touch-screen devices. By the time it became the Touch the iPod basically got transformed into an "iPhone Lite".

Looking through my box of gadgets, I found my old iPod "Video" 5th Generation (model PA003LL) from back in July 2006 (I know this because I got free engraving on it). It's got a 60GB original hard drive installed. Color screen, 2.5", with 320x240 resolution. Firmware version on this baby is 1.3, presumably the latest version since iTunes didn't ask me to update. It still charges fine but there is noticeable degradation with the battery life. The central button feels a little "sticky" these days after many many hours of use over the years, but still functions well. This is the penultimate hard drive based iPod superseded by the iPod "Classic" (6th Gen) in 2007. It has been said that this 5G and "late 2006" 5.5G models with 80GB HD were perhaps the best sounding on account of these models being the last to use a Wolfson DAC internally.

Of interest I think is that Stereophile reviewed and measured an older version of the iPod back in 2003. That was the 3rd Generation they looked at with of course earlier DAC chips.

MEASUREMENTS: PonoPlayer - observations & opinions...

A couple months back, I mentioned that I got myself one of these PonoPlayers. I got it lightly used locally and saved myself quite a few dollars (remember, I'm in Canada so would not be able to buy it directly unless specially shipped across the border). As you can see, I got one of the standard black models. Although the yellow one looks iconic and was what Neil Young went on Letterman with way back in 2012, black is more my style... And it looks pretty cool.

Since its availability back in January 2015, I believe most have no doubt already read a number of reviews on this device... I don't think it's so much the device itself, but the promotion of the whole Pono ecosystem by Neil Young that has ruffled so many feathers in the world of consumer electronics based on his bold claims about the audibility and necessity of "High-Resolution Audio"; claims of an audio "revolution". On one side are the technology sites who view the claims as nothing more than "snake oil", while on the other side - among the "audiophile press" - we see repeated praises of Pono "raising the bar" in its promotion of better sound quality.