Soundcard with S/PDIF out - Quality?


2013-04-02 2:11 pm
Hello! I wonder if there is a difference in quality of the S/PDIF output between different soundcards? I guess this is a pure digital conversation, so there shouldn't be any difference. Am I wrong?

If there is a difference, which technical details are important? (I only care for the S/PDIF output, the analogue outputs are not important in that case.)

Thank you and best regards,

A good spdif out with minimal jitter is preferable. Asus Xonar STX is great for this.
ASUS Xonar Essence ST/STX soundcards |

Word-clock jitter in the STX's TosLink S/PDIF output, measured directly with the AP SYS2722 and a 44.1kHz datastream, was low at 1.48 nanoseconds, which is close to the system's resolution limit. Jitter in the analog output, assessed with the Miller Audio Research analyzer, was very low at 170 picoseconds left and 186ps right. However, this was mainly due to the Miller Analyzer's own noise floor obscuring the picture. (The National Instruments PCI card on which the Analyzer is based uses 16-bit A/D converters.) Graphed with the Audio Precision SYS2722, which has 24-bit converters, a number of sideband pairs can be seen (fig.10); only the highest in level, at ±1.63 and ±3.26kHz, were acknowledged by the Miller Analyzer.