In many review threads, ASR members have reported and discussed all kinds of quirks concerning USB DACs and DAC/HP amp combo devices that can limit those devices' usability. One serious issue is the behavior we call a fade-in or "ramp-up" effect which occurs when playback starts after a device idles for a short time entering its power-saving mode. In this situation, when audio is played the device skips the first second or less of the content. This behavior was reported, for example, in the Fosi Audio DS 2 thread by multiple users.
We must admit that there should be multiple factors in this phenomenon, like the host device, its operating system & settings, playback software, etc. Nonetheless, the information of affected devices and how they are affected should be valuable to potential buyers. Although it is tricky to come up with a testing method, we may still want to have some starting point.
Suggested below is a testing methodology that characterizes these devices' fade-in behavior. Although the testing method is currently only for Windows 11 and foobar2000, with contribution from ASR members the methodology can be expanded and refined.
For the testing environment on Windows 11, the recommendations below, excerpted from this study, were followed:
For the song track to be played in foobar2000 (or any other software) for testing, a song that begins right away with no silence is appropriate. And though not critical, it is interesting to note that the short "Test" chimes in Windows Sound Settings do not cause a device to exit from its power-saving mode in most cases.
With this method, all the USB DAC/HP amps I have in hand were tested. Here are the results:
Note that the FIIO KA15 skips in every test. It is advertised as having very low power consumption. The test results may be attributed to its aggressive power saving scheme. And some do not skip in any test. These include the E1DA 9039S and Qudelix 5K, the designers of which we know are meticulous engineers who pay attention to details.
Here's a link to the spreadsheet "Tests of Fade-In Behavior of DAC/Headphone Amplifiers", which will be updated as more information is collected from ASR members.
Lastly, PLEASE contribute to this compilation of tests by posting results to this thread. The testing environment can be of any kind, depending on which you may want to modify the testing method. I could reorganize the test results as we move on accordingly. And any other suggestions would be considered, too.
We must admit that there should be multiple factors in this phenomenon, like the host device, its operating system & settings, playback software, etc. Nonetheless, the information of affected devices and how they are affected should be valuable to potential buyers. Although it is tricky to come up with a testing method, we may still want to have some starting point.
Suggested below is a testing methodology that characterizes these devices' fade-in behavior. Although the testing method is currently only for Windows 11 and foobar2000, with contribution from ASR members the methodology can be expanded and refined.
For the testing environment on Windows 11, the recommendations below, excerpted from this study, were followed:
- Install Equalizer APO and use it to disable original APOs and set EAPO's preamp gain at ~ -4 dB to avoid upsample overs, filtering induced peaks, and the Windows CAudioLimiter.
- Set Windows audio to 24 bits (or 32 bits if supported) so that its added dither doesn't compromise dynamic range.
- Set Windows sample rate to the same rate as the native file, or to 96 kHz if you play back high resolution material.
- Turn off Windows system sounds and enhancements.
- 10 or more seconds of idling after Windows volume change prompt is heard (volume changed after foobar2000 stopped
); - Shortly after playback is stopped in foobar2000;
- 10 or more seconds after playback is paused
in foobar2000.
- "Test" chimes in Windows Sound Settings
- A song track in foobar2000 (see below to select a suitable song track)
For the song track to be played in foobar2000 (or any other software) for testing, a song that begins right away with no silence is appropriate. And though not critical, it is interesting to note that the short "Test" chimes in Windows Sound Settings do not cause a device to exit from its power-saving mode in most cases.
With this method, all the USB DAC/HP amps I have in hand were tested. Here are the results:
Note that the FIIO KA15 skips in every test. It is advertised as having very low power consumption. The test results may be attributed to its aggressive power saving scheme. And some do not skip in any test. These include the E1DA 9039S and Qudelix 5K, the designers of which we know are meticulous engineers who pay attention to details.
Here's a link to the spreadsheet "Tests of Fade-In Behavior of DAC/Headphone Amplifiers", which will be updated as more information is collected from ASR members.
Lastly, PLEASE contribute to this compilation of tests by posting results to this thread. The testing environment can be of any kind, depending on which you may want to modify the testing method. I could reorganize the test results as we move on accordingly. And any other suggestions would be considered, too.
Last edited:
