This is a review and measurements of the Dosmix USB-C DAC and Headphone Amplifier adapter for phones. It was kindly purchased by a member and drop shipped to me. It is available on Amazon and costs US $21.89 including prime shipping.
From the outside, it is not much different than any other dongle:
Its claim to fame is usage of Qualcomm WHS9415 DAC+headphone amp.
As is typical of some of these adapters, the way they advertise themselves to Windows causes the ASIO wrapper I use to truncate samples to 16 bits. For this reason, the jitter and dashboard views were generated using WASAPI in my media player. For the rest of the tests, I did use the wrapper so there is a slight impact there but not much.
Headphone Adapter Measurements
As usual we start with our dashboard:
There is a mix of good and bad news here. The good news is that the SINAD which is a measure of noise and distortion is quite good for a dongle, likely the best I have measured:
Not so good news is that the output is just shy of 1 volt. And that is with the Windows volume control set to 52. Anything above causes severe clipping. Most dongles cap out at 1 volt but the good ones go up to 2 volts, resulting in much more power being available for high impedance headphones. Not here.
Here is the response as we vary the input digital level:
I set the volume to just above 52 to show the clipping behavior. What this says is that you can turn up the volume way above the distortion-free range of this dongle.
Jitter signal caused severe clipping at anything but the lowest volume. Seems like a bug in the chip. To measure it then I had to lower the volume way down to 12:
Lots and lost of spurious tones there though most dongles have similar issues. There just isn't enough room in there for proper filtering. Your phone by the way may do better than my noisy desktop PC I use for testing. Either way the levels are very low so not audible anyway.
The superior SINAD also translates into superior intermodulation test at the limit:
I did not try to run the dynamic range test as it will be limited by the 16 bit truncation.
Most important measurement for a dongle is power availability. If you run out of that, none of the above figures matter as the volume will either be too low, or distortion too high, or both. Here is the available power at 300 Ohm:
As I predicted, this is not much power at all. My threshold for desktop headphone amps is 100 milliwatts and here we only have 2.8! Here is its ranking as a result:
Switching to 33 ohm load, we get:
Headphone Listening Tests
Keeping the level below 52 gave decent amount of volume with my Sennheiser HD-650 high impedance headphone. Turning up the volume was useful for tracks that were recorded below 0 dB but push it much higher and severe distortion would set in. You get crackling and other artifacts on each bass note.
Going to low impedance Hifiman HE400i generated similar performance.
Conclusions
While the Dosmix dongle has good distortion and noise characteristics, as a headphone amp it just doesn't have much power. If you have an efficient headphone or listen at low volumes, it may do.
For its intended purpose, I can't recommend the Dosmix headphone amplifier. But maybe you can use it as a poor man's desktop DAC.
------------
As always, questions, comments, recommendations, etc. are welcome.
Usually I have excellent reasons for asking for money from you all. But sometimes I don't and but still crave the money. So please donate what you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
From the outside, it is not much different than any other dongle:
Its claim to fame is usage of Qualcomm WHS9415 DAC+headphone amp.
As is typical of some of these adapters, the way they advertise themselves to Windows causes the ASIO wrapper I use to truncate samples to 16 bits. For this reason, the jitter and dashboard views were generated using WASAPI in my media player. For the rest of the tests, I did use the wrapper so there is a slight impact there but not much.
Headphone Adapter Measurements
As usual we start with our dashboard:
There is a mix of good and bad news here. The good news is that the SINAD which is a measure of noise and distortion is quite good for a dongle, likely the best I have measured:
Not so good news is that the output is just shy of 1 volt. And that is with the Windows volume control set to 52. Anything above causes severe clipping. Most dongles cap out at 1 volt but the good ones go up to 2 volts, resulting in much more power being available for high impedance headphones. Not here.
Here is the response as we vary the input digital level:
I set the volume to just above 52 to show the clipping behavior. What this says is that you can turn up the volume way above the distortion-free range of this dongle.
Jitter signal caused severe clipping at anything but the lowest volume. Seems like a bug in the chip. To measure it then I had to lower the volume way down to 12:
Lots and lost of spurious tones there though most dongles have similar issues. There just isn't enough room in there for proper filtering. Your phone by the way may do better than my noisy desktop PC I use for testing. Either way the levels are very low so not audible anyway.
The superior SINAD also translates into superior intermodulation test at the limit:
I did not try to run the dynamic range test as it will be limited by the 16 bit truncation.
Most important measurement for a dongle is power availability. If you run out of that, none of the above figures matter as the volume will either be too low, or distortion too high, or both. Here is the available power at 300 Ohm:
As I predicted, this is not much power at all. My threshold for desktop headphone amps is 100 milliwatts and here we only have 2.8! Here is its ranking as a result:
Switching to 33 ohm load, we get:
Headphone Listening Tests
Keeping the level below 52 gave decent amount of volume with my Sennheiser HD-650 high impedance headphone. Turning up the volume was useful for tracks that were recorded below 0 dB but push it much higher and severe distortion would set in. You get crackling and other artifacts on each bass note.
Going to low impedance Hifiman HE400i generated similar performance.
Conclusions
While the Dosmix dongle has good distortion and noise characteristics, as a headphone amp it just doesn't have much power. If you have an efficient headphone or listen at low volumes, it may do.
For its intended purpose, I can't recommend the Dosmix headphone amplifier. But maybe you can use it as a poor man's desktop DAC.
------------
As always, questions, comments, recommendations, etc. are welcome.
Usually I have excellent reasons for asking for money from you all. But sometimes I don't and but still crave the money. So please donate what you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/