Computer Audio Asylum: S/PDIF quality by John Swenson

Actually the "quality" of s/pdif transmitter is extremely important. I've been doing some experiments with computer s/pdif outputs from several different cards and get radically different results from them. And this is driving a DAC with a very low jitter reclocker and I STILL get significant differences from different s/pdif outputs.

I don't have any experience with either of the two cards in question, but just because you are using the s/pdif output does not mean they will be identical. They could be identical, but they could also be significantly different. There could also be another card that has much better s/pdif output, my experiments don't seem to correlate too well with cost or quality of analog outputs.

I've seen terrible s/pdif results from very expensive outboard boxes and quite good s/pdif results from inexpensive boards. As with all things s/pdif it also depends on the DACs receiver and digital cable used etc.

The other fun thing I'm finding out is that the temperature of the s/pdif transmitter frequently makes a significant difference! If you turn the computer on and start listening, then leave it on and playing music (the speaker don't have to be on) and come back a couple hours later it will sound much better. All experiments seem to indicate this is directly related with the temperature of the digital chips sending out the s/pdif signal. (some boards show this, some don't). This really surprised me but I've heard it happen many times. Maybe thats why sometimes the internal ones can actually sound better, they get hotter sitting inside a poorly ventilated case!

John S.