The Search for Bit Perfect Audio - Part One

Having successfully bypassed the Windows Kmixer, I now want to output the the digital signal from my soundcard to a high quality DAC (in this case the digital input of a Quad 99CDP2). You would think I could just connect the SPDIF out of the Audigy 4 Pro to the SPDIF In of the Quad 99CDPII and hey presto I would have high quality .mp3 playback...if only.

Having spent nearly £200 on this soundcard, I was very dissappointed to discover how the architecture of the Audigy 4 actually worked especially considering all the blurb on the packaging about 24bit Audio. Although the Audigy does indeed input and output 24bit audio, there is one big caveat, the DSP (Digital Signal Processor) at the heart of the Audigy is an EMU10K1 chip. Now although the EMU10K1 is an extremely powerful and competent DSP is does have one major drawback which you won't discover by reading the specifiaction on the box and that is that it is a 16 bit chip, which means that any 24 bit input that you want add effects to etc will need to be down sampled to 16 bit so that the EMU10K1 chip can process it. This also means that any 16bit audio signals such as .mp3 PCM audio has to pass through the DSP and be re-sampled - there is just no way to get bit perfect audio from the SPDIF of an Audigy 4 Pro.
Fortunately there is another chip on the Audgy 4 board that can handle 24bit/96Khz signals and that is the P16V, so it is possible to feed a 24bit/96khz signal into the Audigy and bypass the DSP but to do this requires a special third party driver (Kx Driver) and knowledge of how to upsample the .mp3 file before it reaches the Audigy 4 Pro (the easiest way to do this is to use the ffdshow codec instead of the standard Fraunhofer one).

So there you are I have £200 soundcard that cannot support Bit Perfect Audio so I am back to square one although I thought I was until I stumbled upon a soundcard based around the CMI 8738 chipset which when used with a third party driver supports bit perfect audio and costs a fraction of the Audigy 4 Pro.

This entry was posted on Thursday November 1st, 2007 at 10:33 AM and is filed under MP3 Players. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response.

Leave a Reply

Name (required)
Mail (required - will not be published)
Website


Security Code