Are you looking for the best sound quality for your USB audio, this guide shows you how to setup USB audio in Windows XP and the settings we've found that optimise the sound quality of USB audio equipped DACs, preamplifiers and amplifiers.
Even though this guide shows you how to setup USB audio specifically for Windows XP, many of the concepts are still applicable to Windows Vista and Windows 7 although the settings are accessed via different menus.
At Perreaux, we prefer to use foobar2000 audio player as our audio playback software because it supports almost every audio format known to man, is highly customisable using readily available components and best of all – it doesn't cost a cent.
Download foobar2000 audio player and install it once the download is complete.
The next thing you'll need to do is bypass Windows KMixer. KMixer is the system driver that Windows uses to mix audio streams from different applications, as well as convert sample rates and bit depths, and to control volume levels.
By its very nature KMixer modifies the audio stream and therefore the digital output may not be an exact replication of the source material, i.e. the output is not bit perfect. That's not to say that bit perfect playback is not possible with KMixer, it is possible when setup correctly but the results can be a little hit and miss. A more reliable option for bit perfect playback is to bypass KMixer altogether using ASIO.
ASIO (Audio Stream Input/Output) allows you to bypass Windows KMixer and lets Foobar audio player connect directly to your USB DAC or USB equipped amplifier, improving latency and allowing for a transparent path between the audio player and the hardware.
Note: Your USB DAC or amplifier must support ASIO to use it to bypass Windows KMixer.
Download ASIO4ALL Universal ASIO Driver and install it once the download is complete.
To use ASIO with Foobar audio player you must also download Foobar's ASIO Support component. To install the ASIO Support component copy it to the Foobar "Components" folder (default location C:\Program Files\foobar2000\components).
Start Foobar audio player and open 'Preferences' (File->Preferences). Select the 'ASIO Virtual Devices' pane (Playback->Output->ASIO Virtual Devices) and click Add New.
The ASIO Virtual Device Editor dialog will open, make sure 'ASIO4ALL' is selected in the 'Driver' drop-down menu and map USB Audio Device Channel 1 to 'Left' and USB Audio Device Channel 2 to 'Right'. Click OK to save the settings.
You'll return back to the 'Preferences' window. Select the 'Output' pane (Playback->Output) and from the 'Device' drop-down menu choose 'ASIO : ASIO4ALL'.
That's it for setting ASIO to bypass Windows KMixer. Now to change a couple of Foobar settings to improve your playback experience.
Still in the 'Preferences' window, select the 'Fading' settings (Advanced->Playback->Fading) and click on 'Fade on seek', 'Fade out' and 'Fade on pause' and set each to '0' milliseconds.
Finally, select 'Playback' in the 'Preferences' window. In the 'ReplayGain' section, set both the 'Source mode' and 'Processing' drop-down menus to 'none'.
Click OK to save all the Foobar settings. That does it for setting up Foobar and ASIO4ALL, now we look at optimising Windows XP settings.
To setup Windows XP for best audio performance, we'll configure Windows so the system sounds, such as new mail alerts, playback via the built-in speakers or the on-board sound card. While only the bit perfect music files from Foobar audio player will play through your USB DAC or amplifier.
Open 'Sounds and Audio Devices Properties' (Start->Control Panel->Sounds and Audio Devices), select the 'Audio' tab and from the 'Sound playback' drop-down menu select the on-board sound card. Also, set the 'Use only default devices' checkbox so that Windows doesn't automatically select another audio device when it is connected. Click OK to save the settings.
It is important that your USB DAC or amplifier is connected to a USB 2.0 (Hi-Speed) USB port on your computer. This is mandatory with an asynchronous USB DAC using Class 2 Audio, such as the Perreaux Audiant DP32 USB DAC preamp or 80i integrated amp, since USB 1.1 (Full Speed) doesn't support Class 2 Audio. USB DACs with Class 1 Audio can use either USB 1.1 or USB 2.0 ports, although the increased data rate of USB 2.0 ports (480Mbps vs. 12Mbps) will provide a more reliable interface.
Avoid using the USB ports located on the front of your desktop computer, in our experience the performance can be sketchy and in some cases the front USB ports didn't even support USB 2.0. Ideally your USB DAC should also be running on its own dedicated USB controller and not shared by any other devices or peripherals. To check the DAC is connected a USB 2.0 port and the USB controller is not shared by other devices, open 'System Properties' (Start->Control Panel->System) and in the 'Hardware' tab click 'Device Manager'.
The 'Device Manager' window will open, in the Menu change the view to 'Devices by connection' (View->Devices by connection). Expand all the 'USB Host Controller' entries to see which devices are connected to each controller.
Look for your USB DAC in the list and make sure it is connected to an 'Enhanced' USB controller, this verifies it is connected to a USB 2.0 port. At the same time check that your USB DAC is the only device connected to the 'Enhanced' USB controller, you don't want to share the USB controller with other devices, such as external hard drives, etc.
In the example above you will see that the USB DAC equipped Perreaux Audiant 80i integrated amplifier is connected to a 'Standard Enhanced PCI to USB Host Controller' and it is the only device connected to that USB controller.
Also we do not recommend connecting your USB DAC to the computer via a USB hub as it may result in unreliable performance and cause clicks and dropouts.
While you're in 'Device Manager', open 'Properties' (right-click->Properties) of the 'USB Root Hub' that your USB DAC is connected to. Select the 'Power Management' tab and un-check the 'Allow the computer to turn off this device to save power' checkbox. Click OK to save the settings.
With the Foobar audio player and Windows XP settings optimised, your computer is now setup for the best audio playback with your USB DAC or amplifier. All that's left is a little about audio file formats.
The best performance and sound quality is achieved using an uncompressed file format, such as WAV, which is an exact representation of the original source and doesn't compromise sound quality. The drawbacks with uncompressed audio files are file size and limited support for metadata tagging.
In saying that, the price of storage is so cheap these days, a 1TB HDD costs a smidge over NZ$100 and is capable of holding over 1200 CDs (74 min. @ 16-bit/44.1kHz) or over 190 high resolution albums (74 min. @ 24-bit/192kHz) in uncompressed WAV format. The file size of uncompressed audio formats is really becoming a non-issue as the cost of storage reduces over time.
Tagging on the other hand is a little more problematic, audio players tagging uncompressed audio files is often hit and miss. Many players, including Foobar2000, support tagging uncompressed files, but it's cumbersome and cross-player compatibility is sketchy. For most, this is what kills using uncompressed audio formats – it's just too much of a pain in the butt.
This is where lossless audio compression formats, such as FLAC, come into the mix. Lossless audio files are compressed and the file size is typically 50-55% of the uncompressed files original size. When decompressed during playback, lossless audio files are identical to the original uncompressed file, resulting in no loss of sound quality. Lossless audio formats also have much better support for metadata tagging and album cover art.
If you must use a lossy audio compression format, such as MP3 or AAC, please encode files at the maximum bit rate possible to minimise the impact on sound quality. Lossy compression can achieve significant reductions in file size and does so by discarding information then compressing what remains. When decompressed during playback, information is missing when compared with the original uncompressed file and results in a loss of sound quality.
Due to their smaller file sizes, and excellent support for metadata tagging and cover art, lossy audio formats are perfect to use with portable media players. In our experience, the AAC audio format has better sound quality for a given file size than MP3. Although, outside the context of portable audio, we do not recommend using lossy audio formats for good sound quality.
The FLAC audio file format is our audio format of choice – the file size is smaller than uncompressed, it supports metadata tagging, the lossless compression doesn't compromise sound quality and it is supported natively by foobar2000 audio player.
So there you have it, our view on computer audio and how to setup Windows XP so you get the best sound quality from your USB audio system. USB audio on computer-based systems isn't as scary as it looks; a little effort to set it up reaps massive reward, especially with today's high resolution USB DACs.
Please share your USB audio experiences with us below. Also, if you have any questions, please feel free to ask, we'd be happy to help if we can.
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