Windows for digital audio:
Microsoft Windows has a complete maze of settings when it comes to digital audio. Some of these have a major effect on sound quality. Making sure your PC is set up correctly is the single most important step in getting good audio quality from your PC. My goal here is to make that an easy step by step process. However, I go into a lot of detail that may not be necessary for everyone.
Please note: Every version of Windows does things in a slightly different way. Screenshots will be based on Windows 8.
Back to Basics - Selecting your USB DAC as the output.
The first step is making sure you have the correct device selected. Some USB DAC's will require drivers to work correctly, so make sure you check the manual and check the manufacturers website before continuing.
From Windows Vista on-wards, to select your audio device:
Now, let's try and make it sound better!
The Audio Devices Menu
What's going wrong?
It's quite common for people starting out with USB audio to comment that it doesn't sound as good as their CD player. However, most well set up external DAC's sound significantly better than their CD player equivalents.
There are several issues that cause non perfect audio output on Windows PC's. This article will attempt to go through them one by one.
Sample Rate Conversion
The biggest single initial problem with sound on Windows is that it applies a noisy process called sample rate conversion to your sound.
Windows is designed so that all possible sound sources are mixed together to your output, which means that while you have music playing in the background you can still hear your browser window, games and system sounds.
Unfortunately the way Windows implements this is deeply flawed and severely distorts your music.
Windows automatically converts everything to a single sampling rate, which is usually user defined (or defaults to 48kHz). In many versions of Windows this conversion is done very poorly.
By default Windows will add significant noise, even when your digital output is set to the same frequency as the input file.
The goal with many of these step's is to remove this process as completely as possible.
|The format Selection Menu|
Some higher end DAC's (with ASIO driver support, or kernel streaming) will automatically take care of this for you. This is the best option for most people, as there's no messing around with too many settings involved.
A DAC With Kernel Streaming Support: Myryad Z20
In Windows XP there is no native way to control sampling rate. The default sampling rate conversion is not as terrible as in other versions, but in general, Windows XP is much more difficult (See ASIO4ALL, WASAPI and Foobar2k).
Windows Vista / 7 / 8
Control Panel > Sound > (Select your Audio Device) > Properties > Advanced > Sampling rate
While you are in this menu, make sure both "Exclusive Mode" boxes are ticked. This allows your music playing program to dictate the Sampling Rate if necessary.
Common Audio Formats' Sampling Rates:
CD: 44.1 kHz / 16 Bit
DVD: 48 kHz / 16 Bit
Blu-Ray: 96kHz / 24 Bit
Has that fixed it?
In most cases this is quite close to perfect. There still may be other issues causing non-perfect digital output:
Automatic Sampling Rate Change
The big issue with this solution is the lack of automatic sample rate switching. If you change to a different file with a different sample rate you may be introducing noise again. Some DAC's and soundcards allow you to do this automatically with the correct drivers.
The two most common ways of easily solving this problem are using media players such as Foobar2000 (With WASAPI plug-in or JRiver Media in WASAPI mode). This mutes all other sounds.
A DAC with Integrated Sample Rate Switching: Oppo HA--2
Any program that supports WASAPI output should be suitable.
- Foobar 2000 is available for download, here
Other Possible Issues to think about:
Asynchronous vs Standard USB output:
Asynchronous DAC's take control of the timing information of the signal, which can significantly reduce time domain distortion (jiitter) There is lots (and lots) of information about this on the internet. In most cases there is a significant enough improvement to warrant completely replacing an older USB DAC.
- A well written explanation is available, here
Ground Loop Hums
These are basically caused by ground noise leaking from your PC into your audio device. This is surprisingly common. Basically, there are two ways to solve this. Bring the computer ground and device ground "closer together" by using them on the same circuit, or use a specifically designed USB isolation device.
- Apple has an excellent article on ground loop hum for computer audio here.
Source File Quality
All of this care is completely in vain if you then go and feed your pristine signal crushed low-bitrate MP3's. Well encoded high bit-rate MP3's (Most Streaming Services) are transparent enough that they deserve care, however make sure you use the highest quality possible whenever you have the chance.
- Xiph.org have the simplest and to the point explanation, here