FiiO has released the USBDAC JA11, with an initial price of only $9 (69RMB) and support for PEQ DSD128 PCM384

[jkim]

Just received the JCally JM12 from AliExpress. Unfortunately---I don't know if this is normal---its stock firmware's max volume is set to -6 dB. So, it seems that I have to flash the TinHifi or JA11 firmware just to solve this volume issue alone.

Before I flash the FW---no going back to stock FW---, I measured its response using the KTmicro tool's temporary fix of the volume. But I found that it is difficult to get steady signals from it. See below:

There is absolutely no setting that controls this behavior. It is just random---I can see these erratic responses come and go on rolling FFTs.

Same for the multitone signal:

I initially thought I had received a defective unit. But going over this thread I found another ASR member (@trungdtmc)'s measurements of the FiiO JA11 in this post. The JA11 also showed a similarly distorted multitone response:

I suspect that these measurements explain all the erratic listening test results reported in this thread. I guess I will see the same results even if the TinHifi or JA11 FW is flashed.

 

[markanini]

Just received the JCally JM12 from AliExpress. Unfortunately---I don't know if this is normal---its stock firmware's max volume is set to -6 dB. So, it seems that I have to flash the TinHifi or JA11 firmware just to solve this volume issue alone.

Before I flash the FW---no going back to stock FW---, I measured its response using the KTmicro tool's temporary fix of the volume. But I found that it is difficult to get steady signals from it. See below:
View attachment 462852

There is absolutely no setting that controls this behavior. It is just random---I can see these erratic responses come and go on rolling FFTs.

Same for the multitone signal:
View attachment 462853

I initially thought I had received a defective unit. But going over this thread I found another ASR member (@trungdtmc)'s measurements of the FiiO JA11 in this post. The JA11 also showed a similarly distorted multitone response:
View attachment 462854

I suspect that these measurements explain all the erratic listening test results reported in this thread. I guess I will see the same results even if the TinHifi or JA11 FW is flashed.

Thanks for your measurements. The TinHifi FW makes KTO2H20 the only 1V dongles that can play the Song of the Sisters clip without crackling audibly.

 

[jkim]

Thanks for your measurements. The TinHifi FW makes KTO2H20 the only 1V dongles that can play the Song of the Sisters clip without crackling audibly.

I will flash the TinHifi FW first. I initially hesitated because there's no going back to the original FW and some members reported their preference of the OG FW...

 

[multiformous]

I will flash the TinHifi FW first. I initially hesitated because there's no going back to the original FW and some members reported their preference of the OG FW...

Have you listened to the usual click/crackle test clips with the stock JM12 firmware? I find this dongle to be the worst performer of the bunch of typical rec's (Apple, CX31993). TinHifi FW sounds cleaner than JA11 FW on those clips, but definitely at the cost of a higher noise floor. I also find the JA11 FW slow to ramp up playing from silence (using the Windows sound test button, for example).

 

[jkim]

Have you listened to the usual click/crackle test clips with the stock JM12 firmware? I find this dongle to be the worst performer of the bunch of typical rec's (Apple, CX31993). TinHifi FW sounds cleaner than JA11 FW on those clips, but definitely at the cost of a higher noise floor. I also find the JA11 FW slow to ramp up playing from silence (using the Windows sound test button, for example).

Which test clips specifically?

 

[multiformous]

Which test clips specifically?

The Dune soundtrack test clip, the Cmaj test clip, etc. The same ones used in the CS43xxx tests.

 

[jkim]

Did some more tests of the JM12 with different firmware options.

The erratic, unsteady responses in FFTs are there regardless of firmware. I believe this is a clocking issue. This unsteady response is shown in jitter tests, too. Shown below is a an FFT of a J-test signal when it is normal and steady:

The above is fine performance, but the output signal is not steady. At times, the FFT also becomes:

This instability is there regardless of the FW. One thing notable is that the multitone response observed with the JA11 by @trungdtmc always occurs with the JM12 on JA11 FW:

The JM12 with its stock or TihHifi FW also occasionally shows a similar response:

Recorded the C Major test signal. First up is with the JM12 stock FW:

Not as clear distortion as with CS431xx, but definitely there's distortion along with elevated noise whenever the signal peaks. In particular, there's greater distortion while the signal level increases and decreases.

Same with the JA11 FW:

BUT with the TinHifi FW, we see different behavior:

There is still a distortion but substantially less of it when the signal level increases and decreases. More interesting is its noise level which is definitely higher than with the other two FW options, which is clearly seen when there's a lapse between signals.

It turns out that some kind of dynamic range enhancement (DRE) is involved in some FW options:

I forgot to make the same measurements of the stock FW before flashing, but I'm sure it must have DRE in action as well. Anyway, it appears that DRE is turned off with the TinHifi FW, but turned on with the other two FW options.

This means that the TinHifi FW shows the device's "real" noise performance without DRE. And unsurprisingly it also exhibits less distortion. The dynamic ranges were also measured:

​	Left Ch. DR​	Right Ch. DR​
JM12 w/ TinHifi FW​	102.2 dB​	101.6 dB​
JM12 w/ JA11 FW​	114.3 dB​	112.9 dB​

The DR of TinHifi FW is not that great, but not disastrous, either. You may hear slight hiss with a very sensitive IEM, but will be fine with others. I barely hear hiss using my 7Hz x Crinacle Zero:2.

By the way, I played with the "Noisegate" parameters in the KTmicro tool:

Unfortunately, change of any parameters there has NO effects on measurements at all. Other features like the volume and EQ work, but not this 'Noisegate' feature which is supposed to control the DRE effect.

In any case, I for one will take the elevated noise of the TinHifi FW in exchange of another FW's higher distortion.

However, all in all I wouldn't recommend this device to anyone looking for a cheap PEQ-enabled 1V headphone dongle. Even at less than $10. Why? Because there's an alternative! It is the Hi-Max CB1200AU.

Below is a sneak peak of some measurements of the Hi-Max CB1200AU. First is the recording of the C Major signal played by the Hi-Max:

About the same noise level as the JM12 on TinHifi FW, but there's no distortion at all.

And its dynamic range is also about the same as the JM12 on TinHifi FW:

​	Left Ch. DR​	Right Ch. DR​
Hi-Max CB1200AU​	102.5 dB​	104.0 dB​
JM12 w/ TinHifi FW​	102.2 dB​	101.6 dB​
JM12 w/ JA11 FW​	114.3 dB​	112.9 dB​

And it supports 8-band PEQ that works correctly. What more would you ask for at $6?

I may provide a more extended review of the Hi-Max if I get a chance later...

 

[markanini]

Did some more tests of the JM12 with different firmware options.

The erratic, unsteady responses in FFTs are there regardless of firmware. I believe this is a clocking issue. This unsteady response is shown in jitter tests, too. Shown below is a an FFT of a J-test signal when it is normal and steady:
View attachment 463048

The above is fine performance, but the output signal is not steady. At times, the FFT also becomes:
View attachment 463051

This instability is there regardless of the FW. One thing notable is that the multitone response observed with the JA11 by @trungdtmc always occurs with the JM12 on JA11 FW:
View attachment 463054

The JM12 with its stock or TihHifi FW also occasionally shows a similar response:
View attachment 463056

Recorded the C Major test signal. First up is with the JM12 stock FW:
View attachment 463061
Not as clear distortion as with CS431xx, but definitely there's distortion along with elevated noise whenever the signal peaks. In particular, there's greater distortion while the signal level increases and decreases.

Same with the JA11 FW:
View attachment 463059

BUT with the TinHifi FW, we see different behavior:
View attachment 463058
There is still a distortion but substantially less of it when the signal level increases and decreases. More interesting is its noise level which is definitely higher than with the other two FW options, which is clearly seen when there's a lapse between signals.

It turns out that some kind of dynamic range enhancement (DRE) is involved in some FW options:
View attachment 463064
I forgot to make the same measurements of the stock FW before flashing, but I'm sure it must have DRE in action as well. Anyway, it appears that DRE is turned off with the TinHifi FW, but turned on with the other two FW options.

This means that the TinHifi FW shows the device's REAL noise performance without DRE. And unsurprisingly it also exhibits less distortion. The dynamic ranges were also measured:

​	Left Ch. DR​	Right Ch. DR​
TinHifi FW​	102.2 dB​	101.6 dB​
JA11 FW​	114.3 dB​	112.9 dB​

The DR of TinHifi FW is not that great, but not disastrous, either. You may hear slight hiss with a very sensitive IEM, but will fine with others. I barely hear hiss from my 7Hz x Crinacle Zero:2.

By the way, I played with the "Noisegate" parameters in the KTmicro tool:
View attachment 463070
Unfortunately, change of any parameters there has NO effects on measurements at all. Other features like the volume and EQ work, but not this 'Noisegate' feature which is supposed to control the DRE effect.

In any case, I for one will take the elevated noise of the TinHifi FW in exchange of another FW's higher distortion.

However, all in all I wouldn't recommend this device to anyone looking for a cheap PEQ-enabled 1V headphone dongle. Even at less than $10. Why? Because there's an alternative! It is the Hi-Max CB1200AU.

Below is a sneak peak of some measurements of the Hi-Max CB1200AU. First is the recording of the C Major signal played by the Hi-Max:
View attachment 463060
About the same noise level as the JM12 on TinHifi FW, but there's no distortion at all.

And its dynamic range is also about the same as the JM12 on TinHifi FW:

​	Left Ch. DR​	Right Ch. DR​
Hi-Max CB1200AU​	102.5 dB​	104.0 dB​
JM12 w/ TinHifi FW​	102.2 dB​	101.6 dB​
JM12 w/ JA11 FW​	114.3 dB​	112.9 dB​

And it supports 8-band PEQ that works correctly. What more would you ask for at $6?

I am planning to provide more extended review of the Hi-Max later...

It's fascinating to see the measurements, thanks. It makes me curious if the clocking issue is actually audible, and if there are any sound clips that could highlight it more clearly. The dynamic range difference of 11-12dB, supposedly depending on the DRE is intriguing.

The DR difference reminds me of those who strongly advocate for the Apple dongle referencing a ~10 dB SINAD improvement over other measured dongles in its class. The Apple dongle, using the CS46L41, reportedly produces audible crackling artifacts in "Song of the Sisters" possibly sharing some related DRE technology with the CS43131 and its associated artifacts. The bigger issue is unique OS and regional restrictions that severely limit max output voltage.

The CB1200AU looks impressive, though its relatively high output impedance of 2-2.5 Ohms could audibility alter the frequency response of some IEMs with non-linear impedance curves.

 

[douteiful]

Did some more tests of the JM12 with different firmware options.

The erratic, unsteady responses in FFTs are there regardless of firmware. I believe this is a clocking issue. This unsteady response is shown in jitter tests, too. Shown below is a an FFT of a J-test signal when it is normal and steady:
View attachment 463048

The above is fine performance, but the output signal is not steady. At times, the FFT also becomes:
View attachment 463051

This instability is there regardless of the FW. One thing notable is that the multitone response observed with the JA11 by @trungdtmc always occurs with the JM12 on JA11 FW:
View attachment 463054

The JM12 with its stock or TihHifi FW also occasionally shows a similar response:
View attachment 463056

Recorded the C Major test signal. First up is with the JM12 stock FW:
View attachment 463061
Not as clear distortion as with CS431xx, but definitely there's distortion along with elevated noise whenever the signal peaks. In particular, there's greater distortion while the signal level increases and decreases.

Same with the JA11 FW:
View attachment 463059

BUT with the TinHifi FW, we see different behavior:
View attachment 463058
There is still a distortion but substantially less of it when the signal level increases and decreases. More interesting is its noise level which is definitely higher than with the other two FW options, which is clearly seen when there's a lapse between signals.

It turns out that some kind of dynamic range enhancement (DRE) is involved in some FW options:
View attachment 463064
I forgot to make the same measurements of the stock FW before flashing, but I'm sure it must have DRE in action as well. Anyway, it appears that DRE is turned off with the TinHifi FW, but turned on with the other two FW options.

This means that the TinHifi FW shows the device's REAL noise performance without DRE. And unsurprisingly it also exhibits less distortion. The dynamic ranges were also measured:

​	Left Ch. DR​	Right Ch. DR​
TinHifi FW​	102.2 dB​	101.6 dB​
JA11 FW​	114.3 dB​	112.9 dB​

The DR of TinHifi FW is not that great, but not disastrous, either. You may hear slight hiss with a very sensitive IEM, but will fine with others. I barely hear hiss from my 7Hz x Crinacle Zero:2.

By the way, I played with the "Noisegate" parameters in the KTmicro tool:
View attachment 463070
Unfortunately, change of any parameters there has NO effects on measurements at all. Other features like the volume and EQ work, but not this 'Noisegate' feature which is supposed to control the DRE effect.

In any case, I for one will take the elevated noise of the TinHifi FW in exchange of another FW's higher distortion.

However, all in all I wouldn't recommend this device to anyone looking for a cheap PEQ-enabled 1V headphone dongle. Even at less than $10. Why? Because there's an alternative! It is the Hi-Max CB1200AU.

Below is a sneak peak of some measurements of the Hi-Max CB1200AU. First is the recording of the C Major signal played by the Hi-Max:
View attachment 463060
About the same noise level as the JM12 on TinHifi FW, but there's no distortion at all.

And its dynamic range is also about the same as the JM12 on TinHifi FW:

​	Left Ch. DR​	Right Ch. DR​
Hi-Max CB1200AU​	102.5 dB​	104.0 dB​
JM12 w/ TinHifi FW​	102.2 dB​	101.6 dB​
JM12 w/ JA11 FW​	114.3 dB​	112.9 dB​

And it supports 8-band PEQ that works correctly. What more would you ask for at $6?

I am planning to provide more extended review of the Hi-Max later...

Thanks a lot for the measurements. The DRE finding is interesting. If the crackling occurs specifically in the DRE enabled FWs maybe the crackling is actually caused by the DRE algorithm itself.

Just to add to my experience, I confirm crackling with JM12+JA11 FW. I will try TinHifi's FW as the DR isn't that terrible.
That said, I also have the JM6 (CX31993) and the JM20 (CS43131) and both of these don't have any audible crackling when playing the rumble test, nor any audible hissing for me. It surprises me as I heard the JM6's DAC was technically inferior. Since JM6's power draw is vastly less than the JM20's and it didn't give me any trouble I'll stay with it for now.

How would you compare the technicalities of these three?

 

[jkim]

It's fascinating to see the measurements, thanks. It makes me curious if the clocking issue is actually audible, and if there are any sound clips that could highlight it more clearly. The dynamic range difference of 11-12dB, supposedly depending on the DRE is intriguing.

It will be difficult to evaluate the audible effect of that instability because it randomly comes and goes. It's definitely there but should be hard to spot in real audio content.

DRE's effect becomes larger when the device's thermal noise is relatively higher and benefits more from digital gain. In the case of Apple Macbook's headphone output, the difference is whopping 15 dB:

The DR difference reminds me of those who strongly advocate for the Apple dongle referencing a ~10 dB SINAD improvement over other measured dongles in its class. The Apple dongle, using the CS46L41, reportedly produces audible crackling artifacts in "Song of the Sisters" possibly sharing some related DRE technology with the CS43131 and its associated artifacts. The bigger issue is unique OS and regional restrictions that severely limit max output voltage.

After all the investigation of devices with DRE, I believe we've come up with a one-line summary:

"Basically, all these DRE-enabled devices exchange random, thermal noise for signal-dependent distortion."

I for one do not like this approach and would rather take random noise.

The CB1200AU looks impressive, though its relatively high output impedance of 2-2.5 Ohms could audibility alter the frequency response of some IEMs with non-linear impedance curves.

To me, the actual problem of its slightly high output impedance is a voltage drop for low-impedance (and somewhat insensitive) headphones. The FR change of headphones can always be corrected by PEQ---most headphones and IEMs need correction, anyway. In most cases, the effect of 2-2.5 Ohm output impedance will be tiny.

 

[jkim]

That said, I also have the JM6 (CX31993) and the JM20 (CS43131) and both of these don't have any audible crackling when playing the rumble test, nor any audible hissing for me. It surprises me as I heard the JM6's DAC was technically inferior. Since JM6's power draw is vastly less than the JM20's and it didn't give me any trouble I'll stay with it for now.

I haven't measured any CX31993-based dongle. For now, I think the Hi-Max CB1200AU is the best value among cheap 1V dongles. Headphone-specific PEQ on a tiny, cheap dongle is a great feature since we can simply attach it to a headphone/IEM and forget, and connect it to any USB host device.

 

[danadam]

That said, I also have the JM6 (CX31993) and the JM20 (CS43131) and both of these don't have any audible crackling when playing the rumble test, nor any audible hissing for me. It surprises me as I heard the JM6's DAC was technically inferior. Since JM6's power draw is vastly less than the JM20's and it didn't give me any trouble I'll stay with it for now.

How would you compare the technicalities of these three?

The filter in my JM6 starts to attenuate at around 18.5 kHz when playing audio at 44.1 kHz sampling rate (see in the middle of the post):

Post in thread 'Is Hi-Res Audio better because filter is outside audible range?'

Apr 28, 2025

This can leak ultrasonic noise and trigger IM distortion in the audible passband. Sample slightly faster at 48 kHz to get a slightly wider transition band and the problem disappears.

As far as the danger of IM distortion is concerned, is there a difference between ultrasonics from leaked images of 44.1k sampling rate and in-band ultrasonics of 48k samping rate?

Most of the filters on these DACs (including the WM8741 shown above) fully attenuate by Nyquist at 48 kHz and higher rates.

Not in my experience (but I mostly have cheap dongles). Here's 1 minute of white noise at...

• danadam

• 

 

[markanini]

After all the investigation of devices with DRE, I believe we've come up with a one-line summary:

"Basically, all these DRE-enabled devices exchange random, thermal noise for signal-dependent distortion."

I for one do not like this approach and would rather take random noise.

I agree, the pattern shows up far too frequently to be just an isolated implementation issue.

 

[danadam]

I initially thought I had received a defective unit. But going over this thread I found another ASR member (@trungdtmc)'s measurements of the FiiO JA11 in this post.

Yes, mine has it too: post-1, post-2, post-3 (seems like there are some differences when playing from phone vs from laptop).

Beside that it has:

impulse clipping like my samsung dongle: post

clipping starting from -0.01 dBFS: post

some inter-channel distortion: post-1, post-2

and a distortion during the rumble test: post

That's on the original FW. I haven't tried to update it.

 

[jkim]

Yes, mine has it too: post-1, post-2, post-3 (seems like there are some differences when playing from phone vs from laptop).

Beside that it has:

impulse clipping like my samsung dongle: post

clipping starting from -0.01 dBFS: post

some inter-channel distortion: post-1, post-2

and a distortion during the rumble test: post

That's on the original FW. I haven't tried to update it.

That was you, too! Thanks for the compilation of your work.

 

[jkim]

==============================
Ending the JA11/JM12 firmware uncertainty
==============================

As shown in my earlier post, one main difference between alternative firmware options on this identical KTmicro chip (KT02H20) is the use of DRE (dynamic range enhancement):

This was first discovered by the above measurements.

I ended up testing different firmware options using all known test signals, some of which were contributed by our resident 'test signal expert' @danadam.

1. First up is the Dune soundtrack clip used in the RAA CS431xx sound quality test. This test is best done by varying the signal level. But I was lazy and used a single level set to -9 to -8 dBFS depending on the firmware's max volume. Recordings were all normalized to -1 dBFS.

JM12 firmware (FW):

There's a hint of distortion in the middle.

JA11 FW (V2.2):

Similar level of distortion. It seems that there's greater distortion when the signal level is lower according to @danadam's measurements of the JA11.

TinHifi FW:

Somewhat higher noise, but distortion is barely seen.

2. C Major test tone created by @danadam to test CS431xx-based DACs. Again, played at -9 to -8 dBFS and recordings were normalized to -1 dBFS.

JM12 FW:

Clear distortion especially when the tone starts and ends.

JA11 FW:

The same distortion as with JM12 FW.

TinHifi FW:

Noticeably less distortion in exchange for higher noise.

3. Bandwidth sweep of pulses created by @danadam to show distortion from the Samsung dongle (visit the link to see how this signal was created).

JA11 FW:

Clear distortion.
I couldn't test the JM12 FW with this signal before flashing, but we can make an educated guess that it should distort the same way.

TinHifi FW:

It does not distort!

4. Gain sweep of pulses, another test signal created by @danadam to test the distortion of the Samsung dongle.

JA11 FW:

Distorts clearly.
Again, although I did not test the JM12 stock FW, my informed guess is that it should also distort in response to this signal.

TinHifi FW:

No distortion, again!

5. Audiocheck's Rumble Test tone. Used by many to check if there's a 'crackle' in response to the low-frequency tones in the clip. Played at -26 to -25 dBFS, and the recordings were normalized to -18 dBFS.

JA11 FW:

Yes, it distorts.
Again, I couldn't test the JM12 FW before flashing, but believe the same distortion would occur.

TinHifi FW:

Distortion is barely seen. Somewhat elevated noise level.

6. Inter-channel distortion test signal created by @danadam (see here for how the signal is created). Do not be confused between this distortion and crosstalk. This is a very interesting phenomenon in which one channel's signal does not just bleed into the other channel but projects the same level of distortion to the other channel!

JA11 FW:

Clear distortion in the non-signal channel. Again, I expect the same distortion to occur with the JM12 stock FW.

TinHifi FW:

Absolutely no distortion in the other channel. Only a very little crosstalk.

In conclusion, except for its higher noise level, the TinHifi FW wins all the tests. In fact, I strongly suspect that the reduced noise from the use of DRE is behind all these anomalous distortion results. I'd like to repeat my take on the use of this DRE technique, posted earlier:

Basically, all these DRE-enabled devices exchange random, thermal noise for signal-dependent distortion.

By the way, the Hi-Max CB1200AU passes all these tests with flying colors Will show the results later when I get a chance.

EDIT. As shown earlier, this dongle produces random, erratic FFTs of steady (i.e., constant-level) test signals, regardless of firmware, which I believe is a clocking issue. However, with dynamic (i.e., level-changing) audio signals (i.e., used in the above tests), I couldn't spot distortion suspected to be of the same kind, because the spectrogram results were always consistent over repeated tests, and dependent on particular firmware. Sure, we may still not be comfortable with those FFT results---that is one of the reasons why I don't recommend this dongle for a new purchase---, but already owning it, one could live with it using the TinHifi firmware.

 

[trungdtmc]

The distortions in this chip are random, independent of the firmware. It may be present now, but after stopping playback and turning it back on, it may or may not disappear.

 

[jkim]

The distortions in this chip are random, independent of the firmware. It may be present now, but after stopping playback and turning it back on, it may or may not disappear.

You mean this?

There is absolutely no setting that controls this behavior. It is just random---I can see these erratic responses come and go on rolling FFTs.

The erratic, unsteady responses in FFTs are there regardless of firmware. I believe this is a clocking issue. This unsteady response is shown in jitter tests, too.

This instability is there regardless of the FW. One thing notable is that the multitone response observed with the JA11 by @trungdtmc always occurs with the JM12 on JA11 FW:

Also this?

Yes, mine has it too: post-1, post-2, post-3 (seems like there are some differences when playing from phone vs from laptop).

And that is one of the reasons why I said:

However, all in all I wouldn't recommend this device to anyone looking for a cheap PEQ-enabled 1V headphone dongle.

And upon seeing your post, to avoid confusion, I added:

EDIT. As shown earlier, this dongle produces random, erratic FFTs of steady (i.e., constant-level) test signals, regardless of firmware, which I believe is a clocking issue. However, with dynamic (i.e., level-changing) audio signals (i.e., used in the above tests), I couldn't spot distortion suspected to be of the same kind, because the spectrogram results were always consistent over repeated tests. Sure, we may still not be comfortable with those FFT results---that is one of the reasons why I don't recommend this dongle for a new purchase---, but already owning it, one could live with it using the TinHifi firmware.

Make sense? I suggest recording dynamic audio signals and analyzing the recordings. You will see what I mean. Please let us know if you find inconsistencies across multiple, repeated recordings of the same dynamic audio content.

 

[trungdtmc]

You mean this?



Also this?


And that is one of the reasons why I said:


And upon seeing your post, to avoid confusion, I added:


Make sense? I suggest recording dynamic audio signals and analyzing the recordings. You will see what I mean. Please let us know if you find inconsistencies across multiple, repeated recordings of the same dynamic audio content.

Ok, I see. Randomness here is just between whether or not there is distortion, so measuring it gives some idea of how it will distort. However, my point is that it is not dependent on fixed firmware or hardware.

 

[jkim]

Ok, I see. Randomness here is just between whether or not there is distortion, so measuring it gives some idea of how it will distort. However, my point is that it is not dependent on fixed firmware or hardware.

I still do not see your point clearly. Which distortion shown in which analysis do you mean?

Various distortion phenomena shown in spectrograms across different (dynamic) test signals depend on particular firmware, as shown in my analyses. They are not random but consistently distinct depending on the firmware, especially between the JA11/JM12 versus TinHifi firmware.