Is 75 ohm coax the same as S/PDIF?

It means Sony/Phillips digital interface. It is not always necessary to use 75 ohm; I have used many dedicated digital cables up to ones costing $1500 but right now I am using a standard IC between my transport and DAC.

Thanks for the feedback, but I'm thinking I probably didn't make myself clear: my CD player has a digital out (RCA) that the manual says it's a 75 ohm coax connection. If I get a DAC with S/PDIF input and buy the appropriate cable, will the two work together?

Thanks!

Yes.

Kr, thanks for the straight answer. I'm only hoping you answered the question I think you did!

You asked 2 questions:

Would anyone please clarify?

Clearly, if I had answered this with "Yes," it would be ambiguous.

If I get a DAC with S/PDIF input and buy the appropriate cable, will the two work together?

Yes.

You can make your own 75 ohm connector with good quality belgin 75 ohm coax and good quality RCA connectors. Most people say the proper length for this is 1.5 meters, but I believe a very short run (e.g. 8 inches) also works well (if your DAC will sit right atop your CD player).

Peter_s - you're right about very short runs. Connection is usually considered a transmission line when output transition time is less than 8x propagation time. For typical 25ns transitions found in less expensive transports, assuming 0.7 speed of light, it will be about 2 feet. It might be a serious problem with more expensive transports that can swing in 5ns - our distance would be less than 5". Once we get transmission line effect (reflections on characteristic impedance boundaries) it will be wise to make cable longer to avoid reflection to interfere with the same edge (fastest slew rate is at the beginning of transition). Reflection caused by impedance mismatch (that always happen) coming back fast might interfere with the same transition (creating jitter) but won't be strong enough to cross the threshold in the area after transition - that's why longer (1.5m) cable might be beneficial. I keep it very short - about 6".

It is system (and environment) dependant. Expensive digital cables will make big difference in some systems but won't make any in others. Even Toslink might be good for some systems because it is not creating ground loops.