JCALLY JM20 Headphone Dongle Review

[jkim]

Hi there. Long time reader/lurker, first time writing. Thanks ASR and you all to be my no.1 reality check place to go.

I just purchased a JM20Pro from Ali and I am kind on the situation where I fired first and asking later

My main use case for this dongle is to plug it to a Macbook and feed the 2V out to a Topping L30 II. Basically an ultra compact desktop DAC.
Has anybody here tried it as a DAC only?
If I got it right, volume control here is something purely demanded to the input source - if I max the Macbook volume I get the full 2V out, am I right?
I am amazed how this tiny thing measured so well. Do you see any hidden drawback to use it purely as a DAC? What can be "different" (in audible terms) compared to a dedicated AC powered DAC?

Welcome to the forum!

Exactly what model did you purchase? The JM20Pro or JM20? If it's JM20Pro, unfortunately it is different from the JM20 and produces the "Cirrus Hump" distortion as reported here. You may want to return it and purchase the JM20 or JM20 Max.

The JM20 or JM20 Max will serve your purpose with no problem. No difference from a desktop-size DAC that adopts the same DAC chip.

 

[patoulol]

Welcome to the forum!

Exactly what model did you purchase? The JM20Pro or JM20? If it's JM20Pro, unfortunately it is different from the JM20 and produces the "Cirrus Hump" distortion as reported here. You may want to return it and purchase the JM20 or JM20 Max.

The JM20 or JM20 Max will serve your purpose with no problem. No difference from a desktop-size DAC that adopts the same DAC chip.

Hello

I bought the PRO but it doesn't work (it only works on PC and not on my iphone and ipad)

What do you advise me? take a MAX?

thanks

 

[haivanjv]

Thanks @jkim for the pointer at your new research. Impressive read!

Although I am not that technical to grasp every bit of it, I have some scientific bases to at least try to have a read at the charts.
As I said, unfortunately I already pulled the trigger and the JM20Pro is on its way to me. Maybe not the easiest now to ask for a return from Ali Express.
Nonetheless, I think it might still be fine for my main use case which is feeding a 0db line signal to it. If I did not get it all wrong, the Cirrus hump distortion should go to normal levels from around -15 to 0 dbfs. If I max all volumes on my input source (Macbook vol at max + Spotify or Tidal in exclusive mode), I should set the JM20Pro to play at 0dbfs where there should be no "hump". Can you please help me confirm this? This was connected to my volume control question above: I assume this is purely controlled at the input source.

I don't plan to use it on-the-go as a dongle. For that I have a Qudelix 5k with full feature set and I am very satisfied with it.
My itch was more to have a simple laptop setup when I am listening with the Topping amp.

 

[jkim]

Hello

I bought the PRO but it doesn't work (it only works on PC and not on my iphone and ipad)

What do you advise me? take a MAX?

thanks

Not sure if the Max works on ios correctly. Search in its thread.

 

[jkim]

Thanks @jkim for the pointer at your new research. Impressive read!

Although I am not that technical to grasp every bit of it, I have some scientific bases to at least try to have a read at the charts.
As I said, unfortunately I already pulled the trigger and the JM20Pro is on its way to me. Maybe not the easiest now to ask for a return from Ali Express.
Nonetheless, I think it might still be fine for my main use case which is feeding a 0db line signal to it. If I did not get it all wrong, the Cirrus hump distortion should go to normal levels from around -15 to 0 dbfs. If I max all volumes on my input source (Macbook vol at max + Spotify or Tidal in exclusive mode), I should set the JM20Pro to play at 0dbfs where there should be no "hump". Can you please help me confirm this? This was connected to my volume control question above: I assume this is purely controlled at the input source.

I don't plan to use it on-the-go as a dongle. For that I have a Qudelix 5k with full feature set and I am very satisfied with it.
My itch was more to have a simple laptop setup when I am listening with the Topping amp.

You won't listen to it at 0 dbFS, anyway. It WILL be affected by the distortion.

 

[fws]

Hi there. Long time reader/lurker, first time writing. Thanks ASR and you all to be my no.1 reality check place to go.

I just purchased a JM20Pro from Ali and I am kind on the situation where I fired first and asking later

My main use case for this dongle is to plug it to a Macbook and feed the 2V out to a Topping L30 II. Basically an ultra compact desktop DAC.
Has anybody here tried it as a DAC only?
If I got it right, volume control here is something purely demanded to the input source - if I max the Macbook volume I get the full 2V out, am I right?
I am amazed how this tiny thing measured so well. Do you see any hidden drawback to use it purely as a DAC? What can be "different" (in audible terms) compared to a dedicated AC powered DAC?

I've just ran JM20 with L30 II on Windows, it is not the same dongle, but seemed fine aside the click/pop on start shenanigans which honestly it is better just not to think about. Ye 100% is right, some people will make it 98% out of a habit just to be sure there, which is not an issue as L30 II will still output heaps of power, and the SiNAD will be high enough anyway. I don't count it as a proper 1:1 comparison, because in my setup switching the cable between the sources just takes too long, but JM20 sounds properly ok vs using PCI-e SoundBlaster Z as DAC (102dB SiNAD).

External USB desktop DACs are often still using USB for power, for example a highly popular SMSL SU-1 or the newer, also measured by Amirm, PS200. It is generally assumed that a desktop DAC will have a more robust filtering than a dongle, however it is not like you can't run into a case where some bad designed desktop DAC will have issues despite using a dedicated power supply, while a mere USB dongle runs fine.

 

[Ahmonge]

Not sure if the Max works on ios correctly. Search in its thread

Listening to Jcally JM20 Max on my iPad Air M2 driving my Senns HD 620s: seems to be fully compatible with iPad OS

 

[Billy Budapest]

Not sure if the Max works on ios correctly. Search in its thread.

It works fine.