SPDIF is something to do with Sony Phillips blah blah.
S/PDIF stands for Sony/Phillips Digital Interface (Sony Phillips blah blah would be S/PBB). It's a particular type of digital connection, probably the mosty commonly-used one out there. AES/EBU (Audio Engineering Society/European Broadcast Union) is another type, as is TDIF (Tascam digital interface).
I think the first two are stereo formats (two independent audio channels) -- I'm sure about S/PDIF, not sure abiut AES/EBU.
TDIF is a mutichannel format that carries, I believe, eight separate digital audio tracks, so is commonly found on professional mutlitrack recording equipment, particularly stuff made by Tascam. The ADAT is a recorder made by Alesis (I think it's simply an acronym for Alesis Digtal Audio Tape), also an eight-track unit, and they have their own type of multichannel interface like the Tascam one.
I/O just means input and output. ADAT Sync is a synchronization method employed by ADATs to synch to other ADATs and other devices. Word Clock is another format for locking the timekeeping of digital devices together.
The quality of one form of digital interfacing to another is basically not relevant -- either the data is transferred correctly, or it's not. It's not something like an analog signal where noise can be introduced and the signal can be attenuated and hence degraded slightly from one device to the next.
I hope that helps a bit. As for more techie detail, well, that's just for techies, but if you search a bit through this site:
http://www.studiocovers.com/articles4.htm
no doubt you will find some more specifics.
if i have learnt one thing about computers and music, its this:
If its a jack socket, you need a jack plug. if its a phono socket, you need a phono plug.
anything else is for techies.
A "jack socket" makes no sense; a jack
is a socket. A "jack plug" likewise is gibberish, a plug is what goes into a jack.
A jack and a plug are generic terms and say nothing specific about what type of jack or plug. I suspect what you meant to say was that a 1/8" stereo minijack requires a 1/8" stereo miniplug to connect to it, and a phono jack needs a phono plug...
By the way, phono connectors are often called RCA connectors to make the distinction clearer between the small phono connectors and the larger 1/4" connectors, commonly called phone connectors
There are such things as mono minijacks and plugs too, so if poor iknowmyabcs were to listen to you and go to the store without knowing this he would have a 50/50 chance of choosing the wrong cable. So your curt assertion that "anything else is for techies" is way off too. Not to mention that S/PDIF interfaces often use a standard-looking phono jack, which would never work in a million years with an regular analog audio signal from a RCA cable...
