In this article term "to improve sound quality" mean "to decrease sound playback distortions at the analog output of digital-analog converter". Read below how to try to decrease the playback distortions for your audio equipment or portable device (digital audio player, mobile phone, etc.).
Disclaimer: Result of sound quality improvement method, that described below, depends on used playback hardware and software and sound quality improvement isn't guaranteed.
Digital-analog converter audio hardware may have different distortion levels for different modes. Here DAC mode is a combination of sample rate, bit depth, PCM/DSD.
Different distortions for different DAC modes
One or several modes may have minimal distortions. Below such mode is called as "the best sounding mode".
Audio file resolution may be converted to values (sample rate, bit depth, PCM/DSD) of "the best sounding mode" to improve playback sound quality (optimization of audio files).
Read below about dithering, audio resolution conversion software,
and step-by-step guide on how to check your audio system abilities. Probably it will help to improve the system's sound.
Example:
DAC can be able to provide lesser distortions for mode 192 kHz/24 bit/PCM than for 96 kHz/24 bit/PCM.
Therefore, the conversion of audio file resolution to 192 kHz/24 bit/PCM is recommended for playback at the DAC.
Theoretically, a higher sample rate and bit depth cause lesser noise/distortion level. However, it is an implementation matter rather.
"The best sounding mode" may be found via measurements of the test signals (see at the picture above). However, it demands precise measurement equipment and skills in the measurements.
The article describes step-by-step how to found "the best sounding mode" by ears. It is not a precise way, unlike measurements. But ears allow approximately estimate the DAC's modes at home without additional measurement equipment.
Read more:
In contrast, audio-file-resolution changing, that work together with DAC, dithering allow increasing the sound quality of an audio file as itself in some cases. Because non-linear distortions of quantization, initially correlated with an audio signal, are smoothed and transformed into uncorrelated noise after dithering.
Dither can improve the sound quality of an audio file via correlated distortion decreasing
If DAC has a noise level above the quantization noise of audio file, the dithering impact may be decreased or disappeared even. But modern DACs, as rule, have noise level below 16-bit error quantization and dithering noise. Therefore, for such DAC dithering may impact to perceived sound quality.
Read more:
Below pro audio conversion software is suggested to convert audio files. It has low distortion noise. Theoretically, we can neglect quality losses of conversion (including non-multiple resampling) for pro class of audio converters.
However, different modes of the audio converter's resampling filters may are there, that can cause different ear perception due to different features:
Different converters also have different features of the resampling filters.
Currently, the author knows nothing about reliable results of researches of resampling-filter-features impact to sound perception.
Also, the filtration bandwidth may impact intermodulation distortions at an analog output of DAC.
Read more:
For a purer experiment, audio playback software (audio player and system audio driver) should transfer digital audio data from file to DAC without changes of binary content. As example, a preferable way for audio player software is using ASIO or WASAPI output and turned off processing.
For hardware (devices) adjusting of settings for minimal/without sound processing is recommended.
About digital acoustic-correction of room read below.
Read more:
Read step-by-step guide on how to check your audio system abilities. Probably it will help you to improve the sound.
Described below testing algorithm may be used for DAC, digital audio player, music server, any audio device, that have DAC chip.
In general, for the DAC mode comparison, the author recommends turn off digital room acoustic correction. But you can compare results with the room correction and without.
AuI ConverteR has 3 resampling filter modes (Settings > General > Filter Mode):
Optimized filter cut ultrasound (all above 20 kHz).
Non-optimized filter:
Non-optimized wide filter:
If optimization of audio files gives audible sound advantages in your case, you can convert your audio library to "the best sounding mode"'s parameters: sample rate, bit depth, DSD/PCM.
If in your case no audible sound advantages by optimization, there is not necessary to optimize your library.
It is strongly recommended, original audio files are backup. Because you, probably, will buy new devices or/and new resolution conversion algorithms will be released.
Yuri Korzunov,
Audiophile Inventory's developer
March 15, 2021 updated | since May 09, 2017
Copyright © Yuri Korzunov
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