Glass vs. Plastic optical cables

What happens with the sound if one single bit gets screwed up? Lets say the audio signal is a perfect sine.
Does spdif has any kind of crc checking/error correction?

I don't think so, but it shouldn't need it. UDP is a connectionless protocol that has no kind of error correction and it works great for file transfers and internet/LAN gaming, among other things.

IIRC, the SPDIF protocol uses a form of error correction called "Cross Interleave Reed-Solomon Code" which has 25% redundancy.

Bottom line - if it sounds better to you - that's fine. Just be informed that the human brain is one VERY odd organ, and what may appear to be "A definite change" might be nothing at all (Literally, all in your head )... This is why "Double Blind Tests" will sometimes yeild very different results from what your pre-conceptions would subconciously suggest.

Lol, In some way I think I'm almost willing to say that if it sounds better in your head that is all that matters. In the end that's where the sound is suppose to go.

Isn't "Cross Interleave Reed-Solomon Code" only used internally in compact disc players?

If glass cables with precision machined connectors make you happy, all the more power to you. But that money could be spent elsewhere, with better results, making you even happier

For what it's worth, the toslink standard is actually expecting the normal plastic cables, not glass. So I really don't see how it could make a difference.

Now, that said, I HAVE heard a difference in quality between TOSLINK and a coax S/PDIF connection. Shortly after I got my current receiver, I had both hooked up to two different input selectors. When playing music one time I switched between them and I heard a slight but definitely noticable difference between the two. The coax actually had a slightly clearer sound to it. Where with optical I could hear a slight bit of distortion, when it switched to coax the distortion was less noticable. I couldn't honestly say the frequency response was any better or anything like that, just clarity (I would be hard pressed at this point to say if the sound stage was any better or not either).

I don't know why there was a difference. Certainly I had expected NOT to find one at all, which is why it so surprised me. If I had to guess, I'd say that either the receiver or the DVD player was introducing a slight bit of distortion in the conversion from electrical to optical or vice versa. Of the two I'm more inclined to believe the fault lay with the DVD player.

That was with a PCM audio stream. With encoded formats like dolby digital and dts it shouldn't be possible to have ANY difference between the two.

Edit: DaWiper, you are correct that that error correction is only used internally on the CD player not s/pdif. I have done a bit more research and found a couple of links that go into technical detail on the signals.
http://members.chello.nl/~m.heijligers/DAChtml/digcom/digcom.html

Also if you read the minidisk FAQ it also indicates there is no real error correction with S/PDIF, only parity. One quote that seem to relate to the discussion at hand:

[url=http://www.minidisc.org/faq_sec_4.html#r_q35]What's the scoop on digital connections[/url] said:

SPDIF: (Sony/Philips Digital InterFace): This is the interconnect that is most often used on consumer DAT machines. The connectors are standard RCA phono connectors. This type of connector may also be lableled "IEC Type II" or simply "Digital I/O". Standard analog phono cables can usually be used for the digital data, however some cables that are designed for analog may not be able to carry the high rates needed for the digital data, especially over long distances. Many high-end audio stores carry special digital phono cables that solve this problem. [The pro-audio FAQ says not to use audio cables, but that video cables will work].

Click to expand...

It also linked to this page which seems to contain some nice information on the s/pdif interface and was actually somewhat easier to read than the first link.