which of these cables produces the best audio sound? Also one other "newbie" question. What does it mean to "use the 990's swithcing"? thanks

There always seem to be some debate about optical vs. coax but from my experience I don't feel there is really a noticable difference. Optical cables are abit more fragile in that you have to make sure you don't have any kinks or "hard turns" in your cable run. I run my CD, SAT receiver and DVD with optical but a second CD player and a Squeezebox 3 I use digital coax.

Regarding switching I think you are referring to the 990's video switching. As I run all source video directly into my montitor I'll let someone else address the switching as I have no expereince with it.

I agree with mzpro5. there is no noticeable difference in sound using a optical cable or a coax cable digital cable. both send the digital signal from point A to point B.

some people prefer the coax because it provides a better connection on both ends. An optical cable by compairison seems very unstable and may become loose over time.

As for the "switching" term.. there again is what mzpro said. You connect all your audio and video connections from your SAT, CD, DVD, etc. into the rear of the 990 pre amp. then the 990 pre amp actions like a "switcher" routing the correct audio and video signal for you. It's a bit more complex than that.. but that's the basic idea behind having a processor that does the switching.

Optical and coax digital are the same, 1s and 0s. There is a signal or there's not.

Optical may help you out if you have wiring issues that cuase hum or signal loss.

I've tried both with the same source component and never been able to identify a definite difference.

In general, a coax is a much sturdier connection thus producing far less jitter in the signal. Digital jitter can result in image smearing and other strange anomolies in the sound presentation. If you have the means, I would reccomend using a coax connection over optical with any electronic equipment!!!

Of course, the flip side is that optical (being light) is not susceptible to interference from power cables or speaker cables that are nearby. I tend toward coax over optical when I have the option, but I'm personally not concerned about cases when optical is necessary.

The connection has little to do with jitter. Jitter is the result of a distorted waveform, and since the waveform for a digital signal is only 1 or 0, even a moderately distorted signal is going to be read correctly. To achieve jitter requires massive amounts of signal distortion, and the effects (like loss of dynamic range, clicking, or random phantom tones) are anything but subtle. If you encounter these it's going to be a defective cable, and not an inherent weakness in the type of cable.

Coax and optical cables are used for digital signals for precisely this reason - they are highly resistant (optical is immune) to EFI/RFI. If anyone can point to an A/B comparison that shows a quantifiable difference, I'd be surprised.