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.

Let's have a quick look at this very light, plastic box weighing a mere 60g, measuring 2.25"x3.5"x0.5" not including about another 0.35" at the thickest part with the belt clip. Even though it's light and not the most robust plastic box, it is small with a fair amount of rigidity and has survived a couple of drops on to hardwood flooring already.

This is what the start menu looks like once you select the language and it boots up. The screen is small so the icons and text could be uncomfortably small especially if you have fat fingers when selecting. For the price, the capacitive touchscreen I suppose is reasonable. You'll notice the loss of contrast viewing the screen off-axis as in the image below. Not the best LCD screen but good enough for daily use.

It's nice that there are physical buttons even if a bit loose feeling. Front buttons include a menu button to change options (like setting EQ during playback), there's the music icon button which functions as a play/pause, and exit button for menu navigation.

The left side has 2 buttons at the top for progressing the album track during playback (up button for previous track, down button next track). You can see the TF/microSD slot which is populated by a 32GB generic card that you can swap out (remember to rescan playlist when changing memory cards). At the bottom of the unit are the USB-C connector for data transfer and charging. Data transfer speed fluctuates and will also I suspect depend on the speed of the microSD; I'm seeing only about 5-8MB/s with the included 32GB card which to be honest is still a little faster than the old PonoPlayer!

Beside the USB port is the 3.5mm analogue headphone out which I'll of course be measuring. As I mentioned above, this device is capable of Bluetooth connectivity; I did not have any difficulty with the AirPods Pro Gen2 and 1MORE Sonoflow headphones I tried.

I did not bother testing battery life to any great extent but can say it easily lasted >8 hours with CCA C12 IEMs used off and on around town recently at normal volume. Charging isn't the fastest either but I found that 20 minutes connected to a 5V/1A USB hub was able to get me about 90 minutes of listening time with sensitive IEMs.

On the right are your +/- volume buttons and power button. Note the non-detachable large clip which I found useful. YMMV.

I. Objective Results...

You're probably wondering, for $30 with a touchscreen, Bluetooth, etc. the little DAC inside must be really cheap! How well does this device reproduce audio?

We'll use the RME ADI-2 Pro FS for measurements since I'm not expecting phenomenal performance that would overwhelm the RME! And for completeness, I made sure the firmware is the most recent one online, AGP-A30X-V1.0 dated 2023-11-17, all EQ settings off.

As a start, here's a look at the 1kHz sine wave at maximum volume using the digital oscilloscope:

As you can see, this is a smooth filtered sine wave with maximum output level of 0.5Vrms. Reasonable channel balance with a 0.2dB R-L difference noted at max output (it's down to ~0.1dB at lower amplitudes).

Let's have a look at that digital filter impulse response:

We see a typical linear phase, steep impulse response with the usual Gibbs "ringing"; nothing to worry about. Here's what the "Digital Filter Composite" graph looks like as a reflection of the filtering quality in the frequency domain:

That's pretty good - compare this to the CheapDAC'22! As expected, it's a steep filter that maintains frequencies out to 20kHz without early roll-off, and imaging is well suppressed, even the 19 & 20kHz CCIF intermodulation tones look reasonably clean. There's a small amount of overloading with the wideband white noise signal (up to 0dBFS peaks) but not severe. Also, the noise floor isn't the cleanest with some low-level spurious distortions which will show up later as we examine resolution.

Since this is meant to be a mobile headphone player, let's have a look at the output impedance:

Hmmm, interesting. Clearly this is not an ideal flat impedance curve. Generally, we'd like to see <1Ω across the whole audible spectrum to minimize voltage fluctuations with low-impedance headphones or those with wildly fluctuating impedances (for more see here).

For the AGPTEK, that output impedance rises above 1Ω below 100Hz and peaks at around 3.4Ω at 20Hz. There's potential here for low-impedance headphones (<50Ω) to be significantly bass-shy with this player. Above 100Hz though we should be fine.

Okay, let's now jump into the good-ol' RightMark Audio Analyzer data and graphs comparing a few small headphone DACs. This player is capable of up to 24/48 resolution but since I don't usually measure at 48kHz, let me grab some results at 16/44.1 and 24/44.1. By doing this we can see if 24-bits improved the dynamic range and we can also compare the performance with other devices at 16/44.1:

The first 2 columns are the data for the AGPTEK at 16/44.1 and 24/44.1. Notice that there's basically not much difference. Although the little player can accept 24-bit data, it clearly is not a hi-res device and has noise levels too high to benefit from the extra resolution data. Therefore, consider this a 16-bit device.

As for comparisons to other single-ended devices at 16/44.1, it holds it own. Clearly not as ideal numerically as the E1DA #9038D6K or the Chord Mojo, but otherwise very reasonable results even compared to much more expensive DACs like the iFi Go Bar or Cayin RU6 R-2R (oversampled mode which performed better). Let's look at some graphs for comparison:

The little AGPTEK A30X does a decent job! There's nothing here that looks scary at all. Frequency response is flat unloaded, noise level on par with the others (again, no benefit from 24-bit resolution), good crosstalk down around -85dB, and nothing unusual in the IMD+N sweep. Notice in comparison the poor frequency response of the CheapDAC'22, and the strange IMD+N sweep from the iFi GO Bar.

Everybody loves a 1kHz THD+N/SINAD number, right? Here you go with a 1kHz 24/48 pure sine signal: 🙂

We can see the 0.2dB imbalance between right and left output levels. As expected for the battery-driven device, there's no 60Hz mains hum. It's mostly 2nd harmonic distortion which is unobtrusive. Overall, -85dB THD+N is certainly very reasonable. The CheapDAC'22 only achieved about -70dB THD+N.

For perspective, some of the best single-ended headphone DACs like the E1DA #9038D6K can achieve -120dB THD+N at higher output like 2.5Vrms.

Let's look for jitter - here are the 16-bit and 24-bit Dunn J-Tests:

Not much difference. What's notable is basically the relatively high noise floor which obscures expected elements of the J-Test like components of the LSB 229Hz square jitter modulation tone we would see mainly with the 16-bit test when using hi-res DACs. In any event, the distortion noise and any jitter-related sidebands are below -100dB from the 11 and 12kHz primary signals. Even with a very inexpensive device like this, there's no reason to be concerned about jitter.

As a "standard" measurement among the headphone amps, I've typically used the Triple-Tone Distortion TD+N (48, 960, 5472Hz tones) into a 20Ω load:

Notice the bass droop of the 48Hz tone into a low impedance 20Ω load.

As a low power device, I was only able to push it up to 0.2Vrms unfortunately, compared to the usual 0.5Vrms I measure these at. A result of -53dB on the TD+N isn't good but also not horrific, in fact better than the PonoPlayer's -44dB, but the Pono was able to push 0.4Vrms into the 20Ω load. The Hidizs AP80 PRO-X was able to achieve -87dB at 0.5Vrms (see here for the respective graphs). The CheapDAC'22 isn't a headphone amp so spared from the 20Ω load; nonetheless, it managed only -51dB at ~850mV unloaded.

Finally, I leave it to you to listen for yourself. Here's an AMPT recording (24/96) I made from the output of the device, unloaded so basically acting as a DAC.

AGPTEK A30X Music Player AMPT (EQ OFF)

BTW, can you hear the 0.2dB channel imbalance, left slightly louder?

To wrap up, as you can imagine, this is a very low power device. Into a 20Ω load, this device can achieve ~10mW with <1% THD+N and 3mW into 75Ω. High sensitivity headphones/IEM's recommended.

Over the years, I've used my AKG Q701 headphones with amps to see if they're loud enough as a practical test. The AGPTEK A30X sounded fine with these 62Ω headphones but it clearly did not have enough power to adequately push them IMO. At 100% volume, the sound was merely moderate in volume (I don't think anyone would go deaf!) with good tonality and bass, about what I expected from these open cans.

One feature I appreciate is the ability to listen to FM radio with this (have to plug in the headphones acting as antenna). Channel scanning is fast and holding down the left up/down buttons allow switching between channels. Sound quality is reasonable with good frequency response, low background noise when the signal is strong, but the sound is mono.

II. Subjective impression...

To be honest, as suggested by the title of this article, this is a "utility" music player for me so all I've ever really listened to on the device are high bitrate 320kbps MP3 files. This is the kind of thing I might take on a vacation to listen on the plane or out camping. It's small, light, and out-of-the-way if I just want to clip it to the belt and go for a run either with wired IEMs or Bluetooth headphones (SBC codec only I believe).

Despite the limitations, for the most part, I enjoyed the sound using some inexpensive CCA CRA IEMs I got recently (only US$20). It would have been impossible to achieve this level of sound quality 10 years ago for a mere $50 (A30X player + CCA CRA IEM) in such as small form factor! Even as 320kbps MP3, Vini Vici's electronic compilation Part of the Dream (2017, DR4 only) sounded "tight". Plenty of treble detail, excellent channel separation.

As one might deduce, the main complaint I have is regarding the strength of the bass. Due to the elevated output impedance increasing to 3Ω down into 20Hz, this will audibly affect the bass reproduction of the CCA CRA with a rated impedance of 34Ω in the specs sheet. The bass on a track like "Make Us Stronger" (from Part of the Dream) is enjoyable but clearly not as punchy as I've heard with the CCA CRA using other devices like the Hidizs AP80 PRO-X I reviewed last year; an example of a higher-end, yet still very affordable device. The difference is similar to that between small bass-shy standmount speakers versus full-range towers or adding a good subwoofer.

As an objective-leaning audiophile, it's not good enough for me to just tell you about it of course... Let me show you the frequency response with the different loads: 🤔

As you can see, with the low-impedance CCA-CRA we're about -5.5dB at 30Hz with the AGPTEK A30X player. High sensitivity, higher impedance headphones would be best when paired to this little player.

III. Summary

At a mere US$30 for a digital audio player with touchscreen, 32GB storage, FM reception, convenient clip design, among other features (like even video playback which I didn't try), I think the AGPTEK A30X music player is an interesting example of the functionality at rock-bottom prices available in modern audio devices. Battery life is pretty decent with at least 8 hours music playtime per charge with sensitive IEMs.

Despite the clear output impedance issue affecting bass quantity, I'd still say the value is good. Set your bass quality expectations realistically and you probably won't be too disappointed. 🙂

While the DAC inside this machine must also be very inexpensive, this has significantly better performance than the "CheapDAC'22". I think it's interesting once awhile for context to examine these inexpensive devices to see where the state of sound quality is at on the lowest end of the price spectrum!

This little player could be a good "stocking stuffer" type gift or an inexpensive music player for kids knowing that the headphone output is low power and less likely to cause hearing loss over time depending on headphone sensitivity; not a bad thing to keep in mind these days.

Size comparison of the AGPTEK A30X vs. Hidizs AP80 PRO-X (US$190). Hidizs screen significantly clearer and higher resolution - as expected!

--------------------

EQ...

As we end, let's think about how we can overcome the limitations of the droop with the AGPTEK A30X when listening with lower-impedance headphones. Basically, how do we boost the bass?

There are 2 obvious ways we can try to compensate:

1. Select headphones with inherently strong bass frequency response (despite lower impedance <50Ω) like these:

Those are Sony MDR-XB500 headphones (40Ω impedance) which along with their larger sibling the MDR-XB800, are designed to provide "extra bass". I haven't measured the headphones myself, but here's the frequency response from InnerFidelity back in the day:

These are very comfortable headphones but normally I can't tolerate that amount of bass and sub-bass, but when paired with the AGPTEK, it's actually enjoyable - still quite a bit of midbass hump but without as much very low rumble. 😏

2. Try the EQ feature:

AGPTEK A30X player + CCA CRA IEMs.

There's a simple 7-band graphic equalizer (80/200/500/1k/4k/8k/16k Hz) which is useful. Push that 80Hz up to +3dB while dropping the other frequencies by -1dB or so can help strengthen anemic bass. I wish the EQ settings will show numerically the dB's being adjusted for each band so the user can be more precise with the setting. Obviously the EQ compensation will not be perfect due to the limited bands, so you'll have to experiment to your taste which is also dependent on the specific headphone's frequency response.

Here's a "proof of concept" example of a simple custom EQ for compensation with the CCA CRA IEM load:

Frequency response normalized at 1kHz. Notice 20kHz is anchored to 0dB hench the rise while most other frequencies dropped -1dB. That slight rise in frequencies >10kHz is not easily audible.
(Frequency response captured using averaged continuous white noise.)

I suppose I can pull down the 80Hz by a dB to flatten the mid-bass a bit more but this setting sounds good with improved bass and sub-bass if you're into that kind of sonic signature.

Activating the EQ will change the output volume, and for these settings, there's a net attenuation so be prepared to push the volume up a few notches.

Speaking of EQ, this device has a few presets supposedly meant to be used for various types of music like "Rock", "Jazz", "Funk", "Classic", etc. by adjusting values for the 7-bands. Here's how they measure if you want to imagine using them for compensation:

The "Classic" and "Funk" settings in particular could be helpful to combat the bass droop as well as improve the sound of headphones with high-frequency brightness or harshness. "Rock" and "Jazz" settings present more of the "smiley face curve" that could be subjectively appealing for some. And the "Hip-Hop" is more for vocal/mid-range accentuation, dialing back bass. These could be fun EQ settings to try if you're experimenting with starting points in your own listening.

Over the years, I know that many audiophiles are concerned about deterioration in sound quality by using EQ. Like with all features, DSP could be good or bad. So long as you don't push the gain too high with the music player or software (ie. keep it less than +6dB and compensate with some negative values to reduce risk of clipping), it should sound fine. Yes, there will be some time-domain/phase shifts as well but realize that humans are way more sensitive to frequency changes that time-domain variations, so this should not be a major issue.

Generally, I don't think listeners should shun EQ or DSP - in fact, purely subjective "euphonophiles" should embrace them because all that matters would be the joy the music brings rather than adhering to objective "hi-fi" or "accuracy", right?! I think EQ manipulation can improve the pleasure of music for many audiophiles by customizing to one's taste.

Here's an AMPT file recorded using the "Rock" preset to compare with the AMPT above with EQ off:

AGPTEK A30X Music Player AMPT (EQ = Rock)

As much as it may be exciting to look at and listen to things that are supposedly "worth" four, five, or 6-figures MSRP in audiophile magazines and audio shows, don't forget about the convenience and enjoyment of music that can be had for way, way less these days! (Plus you won't even worry if you damage, totally break or lose something like this.)

Have fun audiophiles!

BTW, checking out the new Dune: Part Two (2024, DR10 2-channel version, as usual higher with multichannel version) soundtrack score this weekend. Have a listen in multichannel/Atmos if you can (Apple Music link); check out "A Time of Quiet Between Storms" for a taste. I quite enjoyed the previous Dune and Dune Sketchbook scores from 2021 although it could at times be a bit too alien and bombastic for some. 👽 Looking forward to the movie in March!