Better PC Sound

Posted at: Friday 29th February 2008 by Chris Lee

Just how good can PC audio be? Chris Lee investigates how to get the best audio quality from your computer, then pits the humble PC against one of the best CD players on the market.

As we wanted to store music on our PC without using compression, our choice of file format was simple. Once we had a selection of songs stored in the uncompressed Wave (WAV) format, the next step was to find the best media playing software with which to play our CD-quality music.

Cost of accurate ripping software: Free


Which media player to use?

As we wanted our PC to produce the best sound possible, the quality that we looked for in our media software was the ability to exercise a high degree of control over how audio is processed and played. As a result, we settled on Winamp (www.winamp.com), which proved to be ideal, as it supports a wide range of plug-ins. As you'll see, these allow you to fine-tune audio playback.

Windows is designed to handle myriad different audio tasks at the same time, from error beeps to complex in-game audio. This is in stark contrast to the obsessive minimalism of a CD player, which has hardware designed solely for converting the digital data from a CD into an electrical analogue signal. Whenever you play a music file in Windows XP, rather than being sent to the motherboard codec directly as a digital PCM stream, the signal will be intercepted by the Windows kernel mixer. The kernel mixer is part of XP's DirectSound API, and was designed so that cheap PC sound cards wouldn't have to handle many audio sources at the same time.

The kernel mixer takes all the audio signals in use at any one time and mixes them into a single stream of data, resampling the music file that you've carefully encoded onto your hard disk. To avoid this resampling, you can use ASIO (Audio Stream Input/Output) sound card drivers. ASIO bypasses any intermediary audio processing on the part of Windows, and instead allows your audio software to communicate with your sound card directly, and vice versa. Winamp can be set to use ASIO via an ASIO output plug-in, but you'll still need ASIO drivers for your sound card.

For the average user, there's a much simpler way to bypass the kernel mixer, which is to use a kernel streaming plug-in for your media player. For Winamp, the kernel streaming plug-in can be downloaded from www.stevemonks.com/ksplugin.

It's important to note that, as you'd expect, given how subjective listening to music is, while some people swear that music sounds cleaner or more detailed when using kernel streaming, others may deny that it has any affect on detail whatsoever. Ultimately, there's no harm in trying it out for yourself, and if nothing else, it's a simple tweak that will also give you a better understanding of how your music software works.

Vista users don't need to worry about kernel streaming. The audio stack was completely rewritten and now supports an audio output mode, called 'exclusive mode', which is very similar to kernel streaming, providing a direct path from an app to audio hardware. The default, however, is 'shared mode'; after each app has mixed its audio, Windows can then apply effects (such as altering volume on a per program basis) before outputting the audio stream to the sound hardware. This may sound like kernel mixing but it's more precise, and offers the user finer grained controls - click on 'manage audio devices' in the Control Panel, and you can investigate the properties of your audio hardware.