Abstract
International Electrotechnical Commission (IEC) and AES standards provide comprehensive tests for the performance of audio analogue to digital (ADC) and digital to analogue (DAC) converters for both consumer and professional applications. It is usually assumed that the ADC is more likely to degrade audio sound quality than the DAC. Tests on two samples of a professional quality PC based audio system are presented that show that a stereo DAC can introduce unexpected non-linear effects. These results suggest that a future revision of the standards should include a measure of inter-channel non-linear cross talk in the stereo DAC. Results are presented and an intermodulation distortion (IMD) loop test proposed to enable this measurement to be made with precision.