Q. Is the quality of S/PDIF connections on soundcards variable?

Is there any difference between the quality of S/PDIF connections on low-end and high-end soundcards, or am I right in thinking that a low-end card with S/PDIF I/O (and the ability to clock from the A-D converter) should be adequate?

Via SOS web site

If a soundcard is well made, its S/PDIF interface should be quality independent, so the difference between low-end and high-end cards should be minimal in this respect.

SOS Technical Editor Hugh Robjohns replies: In theory, S/PDIF is quality independent, assuming that the physical interface is engineered reasonably in the first place. It is purely about transferring the data — there’s no jitter to worry about — so, provided you have decent 75Ω cables of modest length, it should just work. 

I’ve had very few problems with S/PDIF interfaces, and the few issues I did find were actually caused by ground loops.

Personally, I prefer AES3 interfaces, because they will cope with longer cables and are always ground-free, transformer-coupled connections (often S/PDIF is as well, but not always). And XLRs are so much more reliable than RCA phono plugs!  

Published in SOS January 2012